Terminal device and PCRF

ABSTRACT

Communication control for establishing a multi-access PDN connection is performed based on a response to a PDN connectivity establishment request from a terminal device. Communication control for transmitting and/or receiving user data using one or more default bearers for a multi-access PDN connection is performed. This provides a communication control method and the like along with a multi-access PDN connectivity establishment request from the terminal device.

TECHNICAL FIELD

The present invention relates to a terminal device and a PCRF.

BACKGROUND ART

The 3rd Generation Partnership Project (3GPP), which undertakesactivities for standardizing recent mobile communication systems, is inthe process of creating specifications for the Evolved Packet System(EPS), for achieving an all-IP architecture, as described in NPL 1. TheEPS is a mobile communication system through which mobile operators andthe like provide mobile telephone services, and is structured includinga core network called Evolved Packet Core (EPC), an access network basedon the radio communication standard called Long Term Evolution (LTE),and the like.

Furthermore, in the process by the 3GPP of creating EPS specifications,the Network-based IP flow Mobility (NBIFOM) is discussed (see NPL 1).The NBIFOM is a technical item that aims to allow one device tosimultaneously utilize a 3GPP interface and a non-3GPP interface (forexample, WLAN).

In the related art, one PDN connection accommodates a communicationpath, a bearer, or a transfer path through either a 3GPP access network(for example, LTE access network) or a non-3GPP access network (forexample, a WLAN access network).

The NBIFOM maintains a state in which a single PDN connectionsimultaneously accommodates a bearer, a communication path, or atransfer path through a 3GPP access network, and a bearer, acommunication path, or a transfer path through a non-3GPP accessnetwork. Such a single PDN connection is defined as a multi-access PDNconnection.

It is also discussed for the NBIFOM to stipulate an operation modeindicating an anchor node with an initiating function of switching acommunication path. Specifically, it has been discussed for the NBIFOMto classify an operation mode into a UE-initiated mode and aNetwork-initiated mode.

Terminal devices and devices included in a core network and an accessnetwork are capable of transmitting and/or receiving data on acommunication path through an appropriate access network for everyapplication by using an NBIFOM function.

Furthermore, an anchor node configured to initiate switching a flow ofthe multi-access PDN connection established by using the NBIFOM functionis configured based on the operation mode.

CITATION LIST Non Patent Literature

NPL 1: 3GPP TR 23.861 Technical Specification Group Services and SystemAspects, Network based IP flow mobility (Release 13)

SUMMARY OF INVENTION Technical Problem

In the NBIFOM, a detailed procedure for establishing a multi-access PDNconnection is not stipulated.

More specifically, details of accept means from a network for acceptinga request for establishing the multi-access PDN connection, in which aterminal device supports an NBIFOM function, are not clarified.

In light of the foregoing, an object of the present invention is toprovide a suitable way of implementing a communication control procedurein response to a PDN connectivity establishment request from a terminaldevice and communication control using a multi-access PDN connection.

Solution to Problem

In view of above-described problems, in one embodiment of the presentinvention, a terminal device for establishing a Packet Data Network(PDN) connection over a WLAN, the terminal device including:

an LTE interface unit configured to:

-   -   transmit a PDN connectivity request message to a Mobility        Management Entity (MME), in a case where an Evolved Universal        Terrestrial Radio Access Network (E-UTRAN) is added to the PDN        connection, and    -   receive an Activate default EPS bearer context request message        from the MME; and

a control unit.

In a case that a Network-based IP flow mobility (NBIFOM) mode of the PDNconnection is a UE-initiated NBIFOM mode, the PDN connectivity requestmessage includes first information indicating a default access selectedby the terminal device,

the Activate default EPS bearer context request message includes secondinformation indicating a default access determined by a Policy andCharging Rule Function (PCRF) based on the first information, and

the control unit is configured to:

detect the default access indicated by the second information based onreception of the Activate default EPS bearer context request message,and

route a packet not matching any routing filter to the default accessindicated by the second information.

A Policy and Charging Rule Function (PCRF), in another embodiment of thepresent invention, includes:

an IP mobile communication network interface unit configured to:

-   -   receive from a terminal device first information indicating a        default access selected by the terminal device via a Packet Data        Network (PDN) Gateway (PGW), in a case where a Network-based IP        flow mobility (NBIFOM) mode of a PDN connection established by a        terminal device over a WLAN is a UE-initiated NBIFOM mode and an        Evolved Universal Terrestrial Radio Access Network (E-UTRAN) is        to be added to the PDN connection; and

a control unit configured to determine the default access, based on thefirst information, and

the IP mobile communication network interface unit is configured totransmit second information indicating the default access determined bythe control unit to the terminal device via the PGW.

Advantageous Effects of Invention

The present invention enables a communication control procedureaccompanied with a multi-access PDN connectivity establishment requestfrom a terminal device.

Specifically, according to the present invention, a multi-access PDNconnection is established, and communication using the multi-access PDNconnection is enabled.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram illustrating an overview of a mobile communicationsystem.

FIGS. 2A and 2B are diagrams illustrating a configuration of an IPmobile communication network, and the like.

FIG. 3 is a diagram illustrating a functional configuration of a TWAG.

FIGS. 4A to 4E are diagrams illustrating a configuration of a storage ofthe TWAG

FIG. 5 is a diagram illustrating a functional configuration of an HSS.

FIGS. 6A and 6B are diagrams illustrating a configuration of a storageof the HSS.

FIG. 7 is a diagram illustrating a functional configuration of a UE.

FIGS. 8A to 8E are diagrams illustrating a configuration of a storage ofthe UE.

FIG. 9 is a diagram illustrating a functional configuration of a PGW.

FIGS. 10A to 10E are diagrams illustrating a configuration of a storageof the PGW.

FIG. 11 is a diagram illustrating a functional configuration of a PCRF.

FIGS. 12A to 12E are diagrams illustrating a configuration of a storageof the PCRF.

FIG. 13 is a diagram illustrating a state from a first initial state toa state after a PDN connectivity procedure is completed.

FIG. 14 is a diagram illustrating a state from a second initial state toa state after the PDN connectivity procedure is completed.

FIG. 15 is a diagram illustrating a procedure for leading to an initialstate.

FIG. 16 is a diagram illustrating a first PDN connectivity procedure.

FIG. 17 is a diagram illustrating a first additional Attach procedure.

FIG. 18 is a diagram illustrating a PDN connectivity procedure.

DESCRIPTION OF EMBODIMENTS 1. First Embodiment

Hereinafter, a radio communication technology according to an embodimentof the present invention will be described in detail with reference tothe drawings.

1.1. System Overview

FIG. 1 is a diagram illustrating an overview of a mobile communicationsystem according to the present embodiment. As illustrated in FIG. 1, amobile communication system 9 includes a mobile terminal device UE 10,an LTE base station eNB 45 included in an access network A, a TrustedWLAN access gateway (gateway TWAG) 74 included in an access network B, aMobility Management Entity (MME) 40 included in a core network 90, aServing Gateway (SGW) 35, and a PDN Gateway (PGW) 30.

Here, the UE 10 may be any mobile terminal device, and may be a UserEquipment (UE), a Mobile Equipment (ME), or a Mobile Station (MS).

Furthermore, the access network A may be an LTE access network, and theeNB 45 included in the access network A may be an LTE radio basestation. Note that the access network A may include multiple radio basestations. Note that the LTE access network may be an Evolved UniversalTerrestrial Radio Access Network (EUTRAN). Alternatively, the accessnetwork A may be a Universal Terrestrial Radio Access Network (UTRAN) ora GSM EDGE Radio Access Network (GERAN).

Furthermore, the access network B may be a Wireless LAN (WLAN) accessnetwork. The TWAG 74 may be a gateway for connecting to the PGW 30 inthe core network 90, and for connecting the core network 90 and the WLANaccess network.

In the present embodiment, the UE 10 is capable of establishing a PDNconnection using an EPS bearer through the access network A.

Furthermore, the UE 10 is capable of establishing a PDN connection byusing a GTP/PMIPv6 transfer path between the PGW 30 and the UE 10. Notethat the transfer path may be a bearer.

Here, the core network 90 denotes an IP mobile communication network runby a Mobile Operator.

For example, the core network 90 may be a core network 90 for the mobileoperator that runs and manages the mobile communication system 9, or maybe a core network 90 for a virtual mobile operator such as a mobilevirtual network operator (MVNO).

The MME 40 is a control device configured to perform, through the accessnetwork A, location management and access control of the UE 10. Detailsof the MME 40 will be descried later.

Furthermore, the SGW 35 is a gateway device between the core network 90and the access network A, and is configured to transfer user databetween the UE 10 and the PGW 30.

The PGW 30 is a gateway device of a packet data service network (PacketData Network (PDN)) that provides a communication service to the UE 10.

In the present embodiment, the UE 10 is capable of establishing a firstPDN connection and/or a second PDN connection.

Furthermore, in the present embodiment, an NBIFOM is a technology thatallows an establishment of a multi-access PDN connection.

Furthermore, in the present embodiment, the multi-access PDN connectiondenotes a PDN connection capable of accommodating, in one PDNconnection, a transfer path and/or a bearer over a 3GPP access and/or aWLAN access. In other words, the multi-access PDN connection is capableof accommodating both a transfer path through the 3GPP access and atransfer path through the WLAN access. Note that the multi-access PDNconnection may be a PDN connection accommodating only a bearer throughthe 3GPP access or may be a PDN connection accommodating only a transferpath through the WLAN access. In other words, the multi-access PDNconnection denotes a PDN connection capable of constituting one ormultiple transfer paths.

In the present embodiment, to clearly distinguish from a PDN connectionestablished based on an IP Flow Mobility (IFOM), a PDN connection inwhich a transfer path of a certain flow is selectable based on theNBIFOM is defined as “multi-access PDN connection”.

Note that the IFOM is a technology for switching a communication path ofa certain IP flow by using a Dual Stack Mobile IPv6 (DSMIPv6) protocol,and in the present embodiment, a PDN connection capable of switching,based on the IFOM, a communication path of a certain IP flow isdescribed as a PDN connection for the IFOM.

Furthermore, the first PDN connection may be the above-describedmulti-access PDN connection.

In detail, the first PDN connection is a PDN connection in which, as onePDN connection, a communication path EPS bearer through the accessnetwork A and a communication path including a GTP/PMIPv6 tunnel throughthe access network B can be used. That is, such a PDN connection enablestransmission and/or reception of data through the 3GPP access, the WLANaccess, or both thereof. The first PDN connection may be themulti-access PDN connection.

Furthermore, the second PDN connection may be a known PDN connection,rather than the multi-access PDN connection. Note that the second PDNconnection may be a single-access PDN connection.

Here, the single-access PDN connection refers to one PDN connectionconstituted of only a transfer path through either the 3GPP access orthe WLAN access, unlike the multi-access PDN connection. In detail, thesingle-access PDN connection is a PDN connection established by theattach of the related art.

That is, the second PDN connection is a PDN connection including the EPSbearer through the access network A or a PDN connection including theGTP/PMIPv6 transfer path through the access network B. The second PDNconnection accommodates a transfer path and/or a communication paththrough either one of the access networks.

As described above, the single-access PDN connection denotes a PDNconnection that is different from the multi-access PDN connection andthe PDN connection for the IFOM. Moreover, the single-access PDNconnection denotes a PDN connection that is also different from a PDNconnection for a Local IP Access (LIPA). Here, the LIPA denotescommunication control for offloading the connection to a home network.More specifically, the base station to which the terminal deviceconnects performs the offload by transmitting, to the home network towhich the base station connects, user data that is conventionallydelivered via the core network 90. The PDN connection for the LIPA is aPDN connection for performing such communication based on the LIPA.

Next, an example of a configuration of the core network 90 will bedescribed. FIG. 2A illustrates an example of a configuration of the IPmobile communication network. As illustrated in FIG. 2A, the corenetwork 90 includes a Home Subscriber Server (HSS) 50, anAuthentication, Authorization, Accounting (AAA) 55, a Policy andCharging Rules Function (PCRF) 60, the PGW 30, an enhanced Packet DataGateway (ePDG) 65, the SGW 35, the MME 40, and a Serving GPRS SupportNode (SGSN) 45.

Furthermore, the core network 90 is capable of connecting to multipleradio access networks (an LTE AN 80, a WLAN ANb 75, a WLAN ANa 70, aUTRAN 20, and a GERAN 25).

Such a radio access network may be constituted of multiple differentaccess networks, or may be constituted of either one of the accessnetworks. Moreover, the UE 10 is capable of connecting wirelessly to theradio access network.

Moreover, a WLAN Access Network b (WLAN ANb 75) that connects to thecore network 90 via an ePDG 65 and a WLAN Access Network a (WLAN ANa 75)that connects to the PGW 30, the PCRF 60, and the AAA 55 can beconfigured as access networks to be connectable in a WLAN access system.

Note that the devices have a similar configuration to those of thedevices in the related art in a mobile communication system using EPS,and thus a detailed descriptions will be omitted. The devices will bedescribed briefly, hereinafter.

The PGW 30 is connected to the PDN 100, the SGW 35, the ePDG 65, theWLAN ANa 70, the PCRF 60, and the AAA 55, and serves as a relay deviceconfigured to transfer user data by functioning as a gateway devicebetween the PDN 100 and the core network 90.

The SGW 35 is connected to the PGW 30, the MME 40, the LTE AN 80, theSGSN 45, and the UTRAN 20, and serves as a relay device configured totransfer user data by functioning as a gateway device between the corenetwork 90 and the 3GPP access network (the UTRAN 20, the GERAN 25, andthe LTE AN 80).

The MME 40 is connected to the SGW 35, the LTE AN 80, and the HSS 50,and serves as an access control device configured to perform locationinformation management and access control for the UE 10 via the LTE AN80. Furthermore, the core network 90 may include multiple locationmanagement devices. For example, a location management device differentfrom the MME 40 may be constituted. Like the MME 40, the locationmanagement device different from the MME 40 may be connected to the SGW35, the LTE AN 80, and the HSS 50.

Furthermore, when multiple MMEs 40 are included in the core network 90,the MMEs 40 may be connected to each other. With this configuration, thecontext of the UE 10 may be transmitted and/or received among the MMEs40.

The HSS 50 is connected to the MME 40 and the AAA 55, and serves as amanaging node configured to manage subscriber information. Thesubscriber information of the HSS 50 is referenced, for example, in theaccess control for the MME 40. Moreover, the HSS 50 may be connected tothe location management device different from the MME 40.

The AAA 55 is connected to the PGW 30, the HSS 50, the PCRF 60, and theWLAN ANa 70 and is configured to perform access control for the UE 10connected via the WLAN ANa 70.

The PCRF 60 is connected to the PGW 30, the WLAN ANa 75, the AAA 55, andthe PDN 100, and is configured to perform QoS management on datadelivery. For example, the PCRF 60 manages QoS of a communication pathbetween the UE 10 and the PDN 100.

The ePDG 65 is connected to the PGW 30 and the WLAN ANb 75, and isconfigured to deliver user data by functioning as a gateway devicebetween the core network 90 and the WLAN ANb 75.

The SGSN 45 is connected to the UTRAN 20, the GERAN 25, and the SGW 35,and serves as a control device for location management between a 3G/2Gaccess network (UTRAN/GERAN) and the LTE access network (E-UTRAN). Inaddition, the SGSN 45 has a function of selecting the PGW 30 and the SGW35, a function of managing a time zone of the UE 10; and a function ofselecting the MME 40 at the time of handover to the E-UTRAN.

Also, as illustrated in FIG. 2B, each radio access network includesdevices to which the UE 10 is actually connected (for example, a basestation device and an access point device), and the like. The devicesused in these connections are assumed to adapt to the radio accessnetworks.

In the present embodiment, the LTE AN 80 may serve as the E-URANincluding the eNB 45. The eNB 45 is a radio base station to which the UE10 connects in an LTE access system, and the LTE AN 80 may include oneor multiple radio base stations.

The WLAN ANa 70 includes a WLAN APa 72 and the TWAG 74. The WLAN APa 72is a radio base station to which the UE 10 connects in the WLAN accesssystem trusted by the operator running the core network 90, and the WLANANa 70 may include one or multiple radio base stations. The GW 74 is agateway device between the core network 90 and the WLAN ANa 70.Furthermore, the WLAN APa 72 and the GW 74 may be constituted as asingle device.

Even in a case where the operator running the core network 90 and theoperator running the WLAN ANa 70 are different, such a constitution canbe implemented through contracts and agreements between the operators.

Furthermore, the WLAN ANb 75 includes a WLAN APb 76. The WLAN APb 76 isa radio base station to which the UE 10 connects in the WLAN accesssystem in a case that no trusting relationship is established with theoperator running the core network 90, and the WLAN ANb 75 may includeone or multiple radio base stations.

In this manner, the WLAN ANb 75 is connected to the core network 90 viathe ePDG 65, which is a device included in the core network 90, servingas a gateway. The ePDG 65 has a security function for ensuringcommunication security.

The UTRAN 20 includes a radio network controller (RNC) 24 and an eNB(UTRAN) 22. The eNB (UTRAN) 22 is a radio base station to which the UE10 connects through a UMTS Terrestrial Radio Access (UTRA), and theUTRAN 20 may include one or multiple radio base stations. Furthermore,the RNC 24 is a control unit configured to connect the core network 90and the eNB (UTRAN) 22, and the UTRAN 20 may include one or multipleRNCs. Moreover, the RNC 24 may be connected to one or multiple eNBs(UTRANs) 22.

In addition, the RNC 24 may be connected to a radio base station (BaseStation Subsystem (BSS) 26) included in the GERAN 25.

The GERAN 25 includes the BSS 26. The BSS 26 is a radio base station towhich the UE 10 connects through GSM/EDGE radio access (GERA), and theGERAN 25 may be constituted of one or multiple radio base station BSSs.Furthermore, the multiple BSSs may be connected to each other. Moreover,the BSS 26 may be connected to the RNC 24.

Note that in the present specification, the UE 10 being connected toeach radio access network refers to the UE 10 being connected to a basestation device, an access point, or the like included in each radioaccess network, and data, signals, and the like being transmitted and/orreceived also traverse those base station devices, access points, or thelike.

1.2. Device Configuration

Configurations of the devices will be described below.

1.2.1. TWAG Configuration

FIG. 3 illustrates a device configuration of the TWAG 74. As illustratedin FIG. 3, the TWAG 74 includes an IP mobile communication networkinterface unit 320, a control unit 300, and a storage 340. The IP mobilecommunication network interface unit 320 and the storage 340 areconnected to the control unit 300 via a bus.

The control unit 300 serves as a function unit for controlling the TWAG74. The control unit 300 implements various processes by reading out andexecuting various programs stored in the storage 340.

The IP mobile communication network interface unit 320 serves as a datatransmission and/or reception unit configured to transmit and receiveuser data and/or a control message, and serves as a function unitthrough which the TWAG 74 is connected to the PGW 30.

The storage 340 serves as a function unit for storing programs, data,and the like necessary for each operation of the TWAG 74. The storage340 includes, for example, a semiconductor memory, a Hard Disk Drive(HDD), or the like.

As illustrated in FIG. 3, the storage 340 stores a TWAG capability 342,a Network capability 344, and an EPS bearer context 346. Hereinafter,information elements stored in the storage 340 will be described.

FIGS. 4A to 4E illustrate the information elements stored in the storage340. FIG. 4A illustrates an example of the TWAG capability stored in theTWAG 74. In the TWAG capability, identification information (NBIFOMcapability) is stored for each TWAG 74, the information indicatingwhether the capability of establishing the first PDN connection issupported. In other words, the identification information indicateswhether the TWAG 74 supports an NBIFOM function. Specifically, theNBIFOM capability may include “allowed” or “Not allowed”.

Note that the NBIFOM function may be information indicating thepossession of the function of establishing the multi-access PDNconnection.

Alternatively, the NBIFOM capability may be identification informationindicating the possession of the capability of establishing the firstPDN connection. That is, the existence of the NBIFOM capability in thestorage may mean that the TWAG 74 is a gateway capable of establishingthe first PDN connection. In other words, the existence of the NBIFOMcapability in the storage may mean that the TWAG 74 is a gatewaysupporting the NBIFOM function.

As illustrated in FIG. 4A, the NBIFOM capability may be stored inassociation with a TWAG ID that is the identification information on theTWAG 74. In a case of not being associated with the TWAG ID, the NBIFOMcapability may mean a capability of the TWAG 74 to be stored.

If the TWAG ID and the NBIFOM capability are stored in association witheach other, the TWAG 74 may store the TWAG capability of multiple TWAGs74.

In this case, when the UE 10 performs a handover to another TWAG 74, theTWAG 74 may select a TWAG 74 to which the handover is made, based on theTWAG Capability.

Next, the Network capability 344 will be described. FIG. 4B illustratesan example of the Network capability stored in the TWAG 74. In theNetwork capability, the NBIFOM capability is stored for each network,i.e., for each PGW 30.

Here, the NBIFOM capability denotes identification informationindicating whether the capability of establishing the first PDNconnection is supported for each network. In other words, theidentification information indicates whether the PGW 30 supports theNBIFOM function. More specifically, for example, the NBIFOM capabilitymay include “allowed” or “Not allowed”.

Note that the NBIFOM function may be information indicating thepossession of the function of establishing the multi-access PDNconnection.

Alternatively, the NBIFOM capability may be identification informationindicating the possession of the capability of establishing the firstPDN connection. In other words, the NBIFOM capability may beidentification information indicating that a gateway supports the NBIFOMfunction. That is, the existence of the NBIFOM capability in the storagemay mean that the PGW 30 is a gateway having the function ofestablishing the first PDN connection. In other words, the existence ofthe NBIFOM capability in the storage may mean that the PGW 30 is agateway supporting the NBIFOM function.

As illustrated in FIG. 4B, the TWAG 74 stores an NBIFOM capability inassociation with a PGW ID. Furthermore, as illustrated in FIG. 4B, theNBIFOM capability may be stored in association with each of multiplePGWs 30.

The PGW ID may be any information for identifying the PGW 30, and may bean access point name (APN), for example.

Next, an EPS bearer context will be described. The EPS bearer contextmay be classified into the EPS bearer context for each UE 10 stored foreach UE 10, the EPS bearer context for each PDN connection, and the EPSbearer context for each bearer and/or transfer path.

FIG. 4C illustrates information elements included in the EPS bearercontext for each UE 10. As is obvious from FIG. 4C, the TWAG 74 stores,for each UE 10, a UE NBIFOM capability and an NBIFOM allowed.

The UE NBIFOM capability is the NBIFOM capability of the UE 10. The UENBIFOM capability is identification information for each UE 10indicating whether capability of establishing the first PDN connectionis supported. In other words, the UE NBIFOM capability is identificationinformation indicating whether the UE 10 supports the NBIFOM function.More specifically, for example, the UE NBIFOM capability may include“allowed” or “Not allowed”.

Note that the NBIFOM function may be information indicating thepossession of the function of establishing the multi-access PDNconnection.

Alternatively, the UE NBIFOM capability may be identificationinformation indicating that the UE 10 has the capability of establishingthe first PDN connection. That is, the existence of the UE NBIFOMcapability may mean that the UE 10 has a function of establishing thefirst PDN connection.

In other words, the UE NBIFOM capability may be identificationinformation indicating that the UE 10 supports the NBIFOM function. Thatis, the existence of the UE NBIFOM capability in the storage may meanthat the UE 10 supports the NBIFOM function.

Furthermore, the NBIFOM allowed is identification information indicatingan APN, which is allowed to establish a PDN connection using the NBIFOM.The NBIFOM may be associated with at least the APN. The NBIFOM allowedmay be associated with multiple APNs.

In the present embodiment, an APN 1 is associated with the NBIFOMallowed. That is, the APN 1 is allowed to establish the multi-access PDNconnection. In other words, in the present embodiment, the UE 10 isallowed to establish the multi-access PDN connection by using the APN 1.Note that the APN 1 is also allowed to establish the known PDNconnection, rather than the multi-access PDN connection.

In addition, in the present embodiment, an APN 2 is not associated withthe NBIFOM allowed. That is, in the present embodiment, the APN 2 is notallowed to establish a multi-access PDN connection. That is, in thepresent embodiment, the UE 10 is not capable of establishing themulti-access PDN connection by using the APN 2.

The NBIFOM allowed may be stored before the PDN connection isestablished.

The TWAG 74 may access the HSS 50 to acquire the NBIFOM allowed beforethe PDN connection is established and/or during the establishmentprocedure.

Furthermore, the EPS bearer context for each UE 10 may includeidentification information on the UE 10. The identification informationon the UE 10 may be an IMSI.

Furthermore, FIG. 4D illustrates the EPS bearer context for each PDNconnection. The EPS bearer context for each PDN connection includes aPDN connection ID, a Network allowed mode, an Operation mode, a Userplane connection ID, a TWAG MAC address, and an NBIFOM Permission.

The PDN connection ID is identification information for identifying aPDN connection. The UE 10, the TWAG 74, and the PGW 30 may store thesame identification information.

The Operation mode is identification information of a mode thatindicates which one of the UE 10 and a network takes an initiative intransmitting and/or receiving data or is allowed to initiatecommunication control in a case where the PDN connection is the firstPDN connection.

More specifically, for example, an Operation mode that allows the UE 10to initiate the communication control may be the UEinitiated mode.

Furthermore, an Operation mode that allows the network and/or the PGW 30and/or the PCRF 60 to initiate the communication control may be aNetwork initiated mode.

The Network allowed mode indicates an Operation mode allowed by anetwork. The Network allowed mode may include the UEinitiated mode, theNetwork initiated mode, or both thereof.

The User plane connection ID is identification information foridentifying a connection used for transmission of user data in a casewhere the UE 10 establishes a transfer path via the TWAG 74.

A TWAG MAC address is a physical address of the TWAG 74.

The NBIFOM permission is information indicating that this PDN connectionhas established the multi-access PDN connection. In other words, theNBIFOM permission indicates that the first PDN connection has beenestablished.

That is, the TWAG 74 having stored the NBIFOM permission means that thisPDN connection is the first PDN connection.

The NBIFOM permission is identification information that is stored inthe TWAG 74 upon the PDN connection being established.

The TWAG 74 may access the HSS 50 to acquire the NBIFOM permissionduring the establishment of the PDN connection. Alternatively, the TWAG74 may store the NBIFOM Permission, on the basis of the fact that themulti-access PDN connection has been established.

Next, the EPS bearer context for each bearer and/or transfer path willbe described. As illustrated in FIG. 4E, the EPS bearer context for eachbearer and/or transfer path may include transfer path identificationinformation and a Routing Rule.

The transfer path identification information is information foridentifying a transfer path and/or bearer. The transfer pathidentification information may be an EPS bearer ID, for example.

The Routing Rule indicates an association of a Routing Filter with aRouting address or Routing access type. Whether using a communicationpath through the 3GPP access network or using a communication paththrough the WLAN access network is determined, based on such anassociation.

Here, the Routing access type indicates an access network through whichthe flow passes. For example, the Routing access type indicates the 3GPPor the WLAN.

Furthermore, the Routing address indicates an IP address through whichthe flow can pass. For example, the Routing address may be an IP addressof the SGW 35. Alternatively, the Routing address may be an IP addressof the TWAG 74. Alternatively, the Routing address may be an IP addressof a Mobile Access Gateway (MAG).

The Routing Rule may be notified from the PGW 30 or the PCRF 60, or maybe notified from the UE 10. Alternatively, the Routing Rule may be avalue that the TWAG 74 stores beforehand as a default value.

An IP flow may be switched by including an IP header in a RoutingFilter. Alternatively, the flow can be switched for each application byincluding an application ID in the Routing Filter. Alternatively, theRouting Filter may include a TFT.

The Routingu Rule may store multiple rules. Furthermore, the Routingrule may include priority for each rule.

The TWAG Capability and the Network capability may be included in theEPS bearer context.

1.2.2. HSS Configuration

Next, the configuration of the HSS 50 will be described. FIG. 5illustrates a device configuration of the HSS 50. As illustrated in FIG.5, the HSS 50 includes an IP mobile communication network interface unit520, a control unit 500, and a storage 540. The IP mobile communicationnetwork interface unit 520 and the storage 540 are connected to thecontrol unit 500 via a bus.

The control unit 500 serves as a function unit for controlling the HSS50. The control unit 500 implements various processes by reading out andexecuting various programs stored in the storage 540.

The IP mobile communication network interface unit 520 serves as a datatransmission and/or reception unit configured to transmit and/or receiveuser data and/or a control message, and also serves as a function unitfor connecting the HSS 50 to the MME 40 and/or another MME 40, and theAAA 55.

The storage 540 serves as a function unit for storing programs, data,and the like necessary for each operation of the HSS 50. The storage 540includes, for example, a semiconductor memory, a Hard Disk Drive (HDD),or the like.

As illustrated in FIG. 5, the storage 540 stores HSS data 542.Hereinafter, information elements stored in the storage 540 will bedescribed.

FIGS. 6A and 6B illustrate the information elements to be stored in thestorage 540. FIG. 6A illustrates an example of HSS data for each UE 10to be stored in the HSS 50.

As illustrated in FIG. 6A, the HSS data for each UE 10 includes an IMSI,an MSISDN, an IMEI/IMEISV, an Access Restriction, a UE NBIFOMcapability, and an NBIFOM allowed.

The IMSI is identification information to be assigned to a user(subscriber) using the UE 10.

The MSISDN represents the phone number of the UE 10.

The IMEI/IMISV is identification information assigned to the UE 10.

The Access Restriction indicates registration information for an accessrestriction.

The UE NBIFOM capability indicates the NBIFOM capability of the UE 10.The UE NBIFOM capability is identification information for each UE 10indicating whether capability of establishing the first PDN connectionis supported. In other words, the UE NBIFOM capability indicates whetherthe UE 10 supports the NBIFOM function. More specifically, for example,the NBIFOM capability may include “allowed” or “Not allowed”.

Alternatively, the UE NBIFOM capability may be identificationinformation indicating that the UE 10 has the capability of establishingthe first PDN connection. That is, the existence of the UE NBIFOMcapability may mean that the UE 10 has a function of establishing thefirst PDN connection.

Furthermore, the NBIFOM allowed is identification information indicatingan APN that is allowed to establish a PDN connection using the NBIFOM.The NBIFOM may be associated with at least the APN. The NBIFOM allowedmay be associated with multiple APNs.

In the present embodiment, the APN 1 is associated with the NBIFOMallowed. That is, the APN 1 is allowed to establish the multi-access PDNconnection. In other words, in the present embodiment, the UE 10 isallowed to establish the multi-access PDN connection by using the APN 1.Note that the APN 1 is also allowed to establish the known PDNconnection, rather than the multi-access PDN connection.

In addition, in the present embodiment, the APN 2 is not associated withthe NBIFOM allowed. That is, in the present embodiment, the APN 2 is notallowed to establish the multi-access PDN connection. That is, in thepresent embodiment, the UE 10 cannot establish the multi-access PDNconnection by using the APN 2.

The NBIFOM allowed may be stored before the PDN connection isestablished.

FIG. 6B illustrates an example of HSS data for each PDN connectionstored in the HSS 50. As seen from FIG. 6B, the HSS data for each PDNconnection includes at least a Context ID, a PDN address, a PDN Type, anAccess Point Name (APN), a WLAN offload ability, a PDN GW ID, and anNBIFOM Permission.

The Context ID is identification information of the context storing theHSS data for each PDN connection.

The PDN Address represents a registered IP address. The PDN Address isan IP address of the UE 10.

The PDN Type indicates the type of PDN Address. That is, the PDN Type isidentification information for identifying IPv4, IPv6, or IPv4v6, forexample.

The APN is a label indicating an access destination in the network, inaccordance with the DNS naming convention.

The WLAN offload ability is identification information indicatingwhether traffic connected through this APN can perform offload to theWLAN by utilizing a cooperative function between the WLAN and the 3GPP,or maintains the 3GPP connection. The WLAN offload ability may vary foreach RAT type. Specifically, the LTE (E-UTRA) and the 3G (UTRA) may havedifferent WLAN offload ability.

The PDN GW identity is identification information for identifying thePGW 30 utilized in this APN. This identification information may be aFully Qualified Domain Name (FQDN) or an IP address.

The NBIFOM permission is information indicating that this PDN connectionhas established the multi-access PDN connection. In other words, theNBIFOM permission indicates that the first PDN connection has beenestablished.

That is, the TWAG 74 having stored the NBIFOM permission means that thisPDN connection is the first PDN connection.

The NBIFOM permission is identification information that is stored inthe TWAG 74 upon the PDN connection being established.

Specifically, for example, the HSS data for each PDN connectionincluding the APN 1 may include the NBIFOM permission, and the HSS datafor each PDN connection including the APN 2 need not include the NBIFOMpermission.

In other words, the PDN connection based on the APN 1 may be the firstPDN connection, and the PDN connection based on the APN 2 cannot be thefirst PDN connection.

1.2.3. UE Configuration

Next, the configuration of a UE 10 will be described. FIG. 7 illustratesa device configuration of the UE 10. As illustrated in FIG. 7, the UE 10includes an LTE interface unit 720, a WLAN interface unit 740, a controlunit 700, and a storage 750.

The LTE interface unit 720, the WLAN interface unit 740, and the storage750 are connected to the control unit 700 via a bus.

The control unit 700 serves as a function unit for controlling the UE10. The control unit 700 implements various processes by reading out andexecuting various programs stored in the storage 750.

The LTE interface unit 720 serves as a data transmission and/orreception unit configured to transmit and/or receive user data and/or acontrol message, and also serves as a function unit through which the UE10 connects to an IP access network via an LTE base station.Furthermore, an external antenna 710 is connected to the LTE interfaceunit 720.

The WLAN interface unit 740 serves as a data transmission and/orreception unit configured to transmit and/or receive user data and/or acontrol message, and also serves as a function unit through which the UE10 connects to a WLAN AP and connects to the IP access network.Furthermore, an external antenna 730 is connected to the WLAN interfaceunit 740.

The control unit 700 serves as a function unit for controlling the UE10. The control unit 700 implements various processes by reading out andexecuting various programs stored in the storage 750.

The storage 740 is a function unit for storing programs, data, and thelike necessary for each operation of the UE 10. The storage 740 isconstituted of, for example, a semiconductor memory, a hard disk drive(HDD), or the like.

As illustrated in FIG. 7, the storage 750 stores a UE context 752.Hereinafter, information elements stored in the storage 750 will bedescribed. Note that the UE context 752 is classified into a UE contextfor each UE 10, a UE context for each PDN connection, and a UE contextfor each transfer path and/or bearer.

FIG. 8A is an example of the UE context stored for each UE 10. Asillustrated in FIG. 8A, the UE context for each UE 10 includes an IMSI,an EMM State, a GUTI, an ME Identity, and a UE NBIFOM capability.

The IMSI is identification information to be assigned to a user(subscriber) using the UE 10.

The EMM State indicates a mobility management state of the UE 10. Forexample, the EMM State may be EMM-REGISTERED in which the UE 10 isregistered with the network (registered state) or EMM-REREGISTERED inwhich the UE 10 is not registered with the network (reregistered state).

The GUTI is an abbreviation of “Globally Unique Temporary Identity,” andis temporary identification information of the UE 10. The GUTI isconfigured with identification information of the MME 40 (GloballyUnique MME Identifier (GUMMEI)) and identification information of the UE10 in a specific MME 40 (M-TMSI).

The ME identity is an ID of an ME, and may be the IMEI/IMISV, forexample.

The UE NBIFOM capability is the NBIFOM capability of the UE 10. The UENBIFOM capability is identification information for each UE 10indicating whether capability of establishing the first PDN connectionis supported. In other words, the UE NBIFOM capability is identificationinformation for each UE 10 indicating whether the NBIFOM function issupported. More specifically, for example, the NBIFOM capability mayinclude “allowed” or “Not allowed”.

Note that the NBIFOM function may be information indicating thepossession of the function of establishing the multi-access PDNconnection.

Alternatively, the UE NBIFOM capability may be identificationinformation indicating that the UE 10 has capability of establishing thefirst PDN connection. That is, the existence of the UE NBIFOM capabilityin the storage of the UE 10 may mean that the UE 10 has the function ofestablishing the first PDN connection.

In other words, the UE NBIFOM capability may be identificationinformation indicating that the UE 10 supports the NBIFOM function. Thatis, the existence of the UE NBIFOM capability in the storage of the UE10 may mean that the UE 10 supports the NBIFOM function.

FIG. 8B illustrates an example of the UE context for each PDNconnection. As illustrated in FIG. 8B, the UE context for each PDNconnection includes at least a PDN connection ID, an APN in Use, an IPaddress, a Default Bearer, a WLAN offload ability, a UEallowed mode, andan Operation mode.

The PDN connection ID is identification information for identifying aPDN connection. The UE 10, the TWAG 74, and the PGW 30 may store thesame identification information.

The APN in Use is an APN that has been used by the UE 10 most recently.This APN may be constituted of identification information on the networkand identification information on a default operator.

The IP Address is an IP address assigned to the UE 10 through the PDNconnection, and may be an IPv4 address or an IPv6 prefix.

The Default Bearer is EPS bearer identification information foridentifying a default bearer in this PDN connection.

Note that the UE 10 may establish multiple default bearers for a PDNconnection, in a case where the PDN connection is a multi-access PDNconnection. Therefore, the multi-access PDN connection may be managed inassociation with the multiple default bearers. Specifically, EPS beareridentification information corresponding to each default bearer may bemanaged in association with the multi-access PDN connection.

Furthermore, the UE 10 may manage a default bearer and an access networkin association with each other.

Specifically, the UE 10 may store the EPS bearer identificationinformation identifying each of the default bearer for the accessnetwork A and the default bearer for the access network B. Here, thedefault bearer for an access network may be a default bearer for anaccess system of the access network. Therefore, the UE 10 may store adefault bearer for a 3GPP access and a default bearer for a WLAN accessin association with a multi-access PDN connection.

The default bearer for the multi-access PDN may be a default bearerestablished by the UE 10. In other words, the UE 10 stores one defaultbearer for the multi-access PDN connection in a state where only onedefault bearer is established for the multi-access PDN connection, andthe UE 10 may store two default bearers for the multi-access PDNconnection in a state where two default bearers are established for themulti-access PDN connection.

Furthermore, the UE 10 may store, with respect to the multi-access PDNconnection, information indicating default access (Default Assess) inthe multi-access PDN connection. Note that the default access may beinformation indicating the 3GPP access or the WLAN access. The 3GPPaccess may be an access system that is not the WLAN access. Morespecifically, the 3GPP access may be information indicating an accessnetwork including an E-UTRAN access, a UTRAN access, and a GERAN access.

Alternatively, the default access may include more detailed information.For example, the default access may be one of E-UTRAN access, UTRANaccess, and GERAN access.

In a case where multiple default bearers are established, the UE 10 mayselect a default bearer based on the default access, and may transmitand/or receive user data by using the selected default bearer.

The WLAN off loadability is WLAN offload permission informationindicating whether a communication associated with the PDN connection isallowed for offload to the WLAN using an interworking function betweenthe WLAN and the 3GPP, or maintains the 3GPP access.

The UE allowed mode is an operation mode allowed by the UE 10. Thisidentification information may indicate the UE intiated mode, theNetwork initiated mode, or both thereof.

The Operation mode is identification information on a mode thatindicates which of the UE 10 and the network takes an initiative intransmitting and/or receiving data or is allowed to initiatecommunication control in a case that the current PDN connection is thefirst PDN connection.

FIG. 8C illustrates the UE context for each bearer. The UE context foreach bearer includes transfer path identification information and aRouting Rule.

The transfer path identification information is information foridentifying a transfer path and/or bearer. The transfer pathidentification information may be an EPS bearer ID, for example.

Furthermore, the transfer path identification information may beassociated with the TFT.

Here, the Routing access type indicates an access network through whichthe flow passes. For example, the Routing access type indicates the 3GPPor the WLAN.

Furthermore, the Routing address indicates an IP address through whichthe flow can pass. For example, the Routing address may be an IP addressof the SGW 35. Alternatively, the Routing address may be an IP addressof the TWAG 74. Alternatively, the Routing address may be an IP addressof a Mobile Access Gateway (MAG).

The Routing Rule may be notified from the PGW 30 or the PCRF 60.Alternatively, the Routing Rule may be a value that the UE 10 prestoresas a default value.

An IP flow may be switched by including an IP header in a RoutingFilter. Alternatively, the UE 10 may switch the flow for eachapplication by including an application ID in the Routing Filter.Alternatively, the Routing Filter may include a TFT.

The Routingu Rule may store multiple rules (regulations). Furthermore,the Routing rule may include priority for each rule.

FIG. 8D illustrates the TWAG Capability. In the TWAG capability,identification information (NBIFOM capability) is stored for each TWAG74, the information indicating whether the capability of establishingthe first PDN connection is supported. In other words, theidentification information indicates whether the TWAG 74 supports anNBIFOM function. Specifically, the NBIFOM capability may include“allowed” or “Not allowed”.

Note that the NBIFOM function may be information indicating thepossession of the function of establishing the multi-access PDNconnection.

Alternatively, the NBIFOM capability may be identification informationindicating the possession of the capability of establishing the firstPDN connection. That is, the existence of the NBIFOM capability in thestorage may mean that the TWAG 74 is a gateway capable of establishingthe first PDN connection. In other words, the existence of the NBIFOMcapability in the storage may mean that the TWAG 74 is a gatewaysupporting the NBIFOM function.

The UE 10 may store the NBIFOM capability associated with the TWAG ID.Furthermore, the NBIFOM capability of multiple TWAGs 74 may be stored.

FIG. 8E illustrates an example of the Network capability. In the Networkcapability, the NBIFOM capability is stored for each network, i.e., foreach PGW 30.

Here, the NBIFOM capability denotes identification informationindicating whether the capability of establishing the first PDNconnection is supported for each network. More specifically, forexample, the NBIFOM capability may include “allowed” or “Not allowed”.

Alternatively, the NBIFOM capability may be identification informationindicating the possession of the capability of establishing the firstPDN connection. That is, the existence of the NBIFOM capability may meanthat the PGW 30 and/or the network is a gateway having the function ofestablishing the first PDN connection.

As illustrated in FIG. 8E, the TWAG 74 stores the NBIFOM capability inassociation with the PGW ID. Furthermore, as illustrated in FIG. 8E, theNBIFOM capability may be stored in association with each of multiplePGWs 30.

The PGW ID is information for identifying the PGW 30. The PGW ID may bean APN, for example.

The TWAG Capability and the Network capability may be included in the UEcontext, or may be information separated from the UE context.

That is, the UE 10 may store the TWAG Capability and the Networkcapability included in the UE context, or may store the TWAG Capabilityand the Network capability separately from the UE context.

1.2.4. PGW Components

Next, the components of the PGW 30 will be described. FIG. 9 illustratesa device configuration of the PGW 30. As illustrated in FIG. 9, the PGW30 includes an IP mobile communication network interface unit 920, acontrol unit 900, and a storage 940. The IP mobile communication networkinterface unit 920 and the storage 940 are connected to the control unit900 via a bus.

The control unit 900 serves as a function unit for controlling the PGW30. The control unit 900 implements various processes by reading out andexecuting various programs stored in the storage 940.

The IP mobile communication network interface unit 920 serves as a datatransmission and reception unit configured to transmit and/or receiveuser data and/or a control message, and also serves as a function unitthrough which the PGW 30 is connected to the SGW 35 and/or the PCRF 60and/or the ePDG 65 and/or the AAA 55 and/or the GW 74.

The storage 940 serves as a function unit for storing programs, data,and the like necessary for each operation of the PGW 30. The storage 940is configured with, for example, a semiconductor memory, a Hard DiskDrive (HDD), or the like.

As illustrated in FIG. 9, the storage 940 stores an EPS bearer context942. Note that an EPS bearer context includes an EPS bearer contextstored for each UE 10, an EPS bearer context stored for each APN, an EPSbearer context stored for each PDN connection, and an EPS bearer contextstored for each transfer path and/or bearer.

First, the EPS bearer context for each UE 10 will be described. FIG. 10Aillustrates an example of the EPS bearer context for each UE 10. Asillustrated in FIG. 10A, the EPS bearer context includes at least anIMSI, an ME identity, an MSISDN, and a UE NBIFOM capability.

The IMSI is information for identifying a user of the UE 10.

The ME identity is an ID of an ME, and may be the IMEI/IMISV, forexample.

The MSISDN represents the phone number of the UE 10.

The UE NBIFOM capability is the NBIFOM capability of the UE 10. The UENBIFOM capability is identification information for each UE 10indicating whether the UE 10 has capability of establishing the firstPDN connection. More specifically, for example, the NBIFOM capabilitymay include “allowed” or “Not allowed”.

Alternatively, the UE NBIFOM capability may be identificationinformation indicating that the UE 10 has the capability of establishingthe first PDN connection. That is, the existence of the UE NBIFOMcapability may mean that the UE 10 has a function of establishing thefirst PDN connection.

Next, the EPS bearer context for each PDN connection will be described.FIG. 10B illustrates an example of the EPS bearer context for each PDNconnection.

As illustrated in FIG. 10B, the context includes at least a PDNconnection ID, an IP address, a PDN type, an APN, a Network allowedmode, and an Operation mode.

The PDN connection ID is identification information for identifying aPDN connection. The UE 10, the TWAG 74, and the PGW 30 may store thesame identification information.

The IP Address indicates an IP address assigned to the UE 10 for the PDNconnection. The IP address may be an IPv4 and/or IPv6 prefix.

The PDN type indicates the type of the IP address. The PDN typeindicates IPv4, IPv6, or IPv4v6, for example.

The APN is a label indicating an access destination in the network, inaccordance with the DNS naming convention.

The Network allowed mode indicates an Operation mode allowed by thenetwork. The Network allowed mode may include the UEinitiated mode, theNetwork initiated mode, or both thereof.

The Operation mode is identification information of a mode thatindicates which one of the UE 10 and a network takes an initiative intransmitting and/or receiving data or is allowed to initiatecommunication control in a case where the current PDN connection is thefirst PDN connection.

More specifically, for example, the UE initiated mode in which the UE 10is allowed to initiate the communication control or the Networkinitiated mode in which the network is allowed to initiate thecommunication control may be identified.

Next, an example of the EPS bearer context for each transfer path and/orbearer will be described with reference to FIG. 10C. As illustrated inFIG. 10C, the context includes at least transfer path identificationinformation and a Routing Rule.

The transfer path identification information is information foridentifying a transfer path and/or bearer. The transfer pathidentification information may be an EPS bearer ID, for example.

Furthermore, the transfer path identification information may beassociated with the TFT.

The Routing access type indicates an access network through which theflow passes. For example, the Routing access type indicates the 3GPP orthe WLAN.

Furthermore, the Routing address indicates an IP address through whichthe flow can pass. For example, the Routing address may be an IP addressof the SGW 35. Alternatively, the Routing address may be an IP addressof the TWAG 74. Alternatively, the Routing address may be an IP addressof a mobile access gateway (MAG).

The Routing Rule may be notified from the PGW 30 or the PCRF 60.Alternatively, the Routing Rule may be a value that the UE 10 prestoresas a default value.

The PGW 30 may switch the IP flow by including an IP header in theRouting Filter. Alternatively, the PGW 30 may switch the flow for eachapplication by including an application ID in Routing Filter.Alternatively, the Routing Filter may include a TFT.

The Routingu Rule may store multiple rules. Furthermore, the Routingrule may include priority for each rule.

Furthermore, the PGW 30 may establish the default bearer for each PDNconnection established with the UE 10, and store the EPS beareridentification information identifying the default bearer.

Note that the PGW 30 may establish multiple default bearers for a PDNconnection, in a case where the PDN connection is a multi-access PDNconnection. Therefore, the multi-access PDN connection may be managed inassociation with the multiple default bearers. Specifically, EPS beareridentification information corresponding to each default bearer may bemanaged in association with the multi-access PDN connection.

Furthermore, the PGW 30 may manage the default bearers and the accessnetwork in association with each other.

Specifically, the PGW 30 may store the EPS bearer identificationinformation identifying each of the default bearer for the accessnetwork A and the default bearer for access network B. Here, the defaultbearer for an access network may be a default bearer for an accesssystem of the access network. Therefore, the PGW 30 may store thedefault bearer for 3GPP access and the default bearer for a WLAN accessin association with the multi-access PDN connection.

The default bearer for the multi-access PDN may be a default bearer thatis being established between the PGW 30 and the UE 10. In other words,the PGW 30 stores one default bearer for the multi-access PDN connectionin a state where only one default bearer is established for themulti-access PDN connection, and the PGW 30 may store two defaultbearers for the multi-access PDN connection in a state where two defaultbearers are established for the multi-access PDN connection.

Furthermore, the PGE 30 may store information indicating a defaultaccess (Default Assess) in the multi-access PDN connection, for themulti-access PDN connection. Note that the default access may beinformation indicating the 3GPP access or the WLAN access. The 3GPPaccess may be an access system that is not the WLAN access. Morespecifically, the 3GPP access may be information indicating an accessnetwork including the E-UTRAN access, the UTRAN access, and the GERANaccess.

Alternatively, the default access may include more detailed information.For example, the default access may be one of E-UTRAN access, UTRANaccess, and GERAN access.

When multiple default bearers are established, the PGW 30 may select adefault bearer based on the default access, and transmit and/or receiveuser data by using the selected default bearer.

FIG. 10D illustrates the TWAG Capability. In the TWAG capability,identification information (NBIFOM capability) is stored for each TWAG74, the information indicating whether the capability of establishingthe first PDN connection is supported. In other words, theidentification information indicates whether the TWAG 74 supports anNBIFOM function. Specifically, the NBIFOM capability may include“allowed” or “Not allowed”.

Note that the NBIFOM function may be information indicating thepossession of the function of establishing the multi-access PDNconnection.

Alternatively, the NBIFOM capability may be identification informationindicating the possession of the capability of establishing the firstPDN connection. That is, the existence of the NBIFOM capability in thestorage may mean that the TWAG 74 is a gateway capable of establishingthe first PDN connection. In other words, the existence of the NBIFOMcapability in the storage may mean that the TWAG 74 is a gatewaysupporting the NBIFOM function.

The PGW 30 may store the NBIFOM capability associated with the TWAG ID.

FIG. 10E illustrates an example of the Network capability. In theNetwork capability, the NBIFOM capability is stored for each network,i.e., for each PGW 30.

Here, the NBIFOM capability denotes identification informationindicating whether the capability of establishing the first PDNconnection is supported for each network. More specifically, forexample, the NBIFOM capability may include “allowed” or “Not allowed”.

Alternatively, the NBIFOM capability may be identification informationindicating the possession of the capability of establishing the firstPDN connection. That is, the existence of the NBIFOM capability may meanthat the PGW 30 and/or the network is a gateway having the function ofestablishing the first PDN connection.

As illustrated in FIG. 10E, the PGW 30 stores the NBIFOM capability inassociation with the PGW ID. Furthermore, as illustrated in FIG. 10E,the NBIFOM capability may be stored in association with each of themultiple PGWs 30.

The PGW ID may be any information for identifying the PGW 30, and may bean APN, for example.

The TWAG Capability and the Network capability may be included in theEPS bearer context, or may be information separated from the UE context.

1.2.5. PCRF Components

Next, the components of the PCRF 60 will be described. FIG. 11illustrates a device configuration of the PCRF 60. As illustrated inFIG. 11, the PCRF 60 includes an IP mobile communication networkinterface unit 1120, a control unit 1100, and a storage 1140. The IPmobile communication network interface unit 1120 and the storage 1140are connected to the control unit 1100 via a bus.

The control unit 1100 serves as a function unit for controlling the PCRF60. The control unit 1100 implements various processes by reading outand executing various programs stored in the storage 1140.

The IP mobile communication network interface unit 1120 serves as a datatransmission and/or reception unit configured to transmit and/or receiveuser data and/or a control message, and also serves as a function unitthrough which the PCRF 60 is connected to the PGW 30 and/or the TWAG 74and/or the AAA 55.

The storage 1140 serves as a function unit for storing programs, data,and the like necessary for each operation of the PCRF 60. The storage940 is configured with, for example, a semiconductor memory, a Hard DiskDrive (HDD), or the like.

As illustrated in FIG. 11, the storage 1140 stores UE context 1142. Notethat the UE context may be classified into a UE context stored for eachUE 10 and a UE context stored for each PDN connection.

FIG. 12A illustrates the UE context for each UE 10. As illustrated inFIG. 12A, the context includes at least a Subscriber ID and UE NBIFOMcapability.

The Subscriber ID is identification information of a user. For example,the subscriber ID may be an IMSI.

The UE NBIFOM capability is the NBIFOM capability of the UE 10. The UENBIFOM capability is identification information for each UE 10indicating whether capability of establishing the first PDN connectionis supported. In other words, the UE NBIFOM capability is identificationinformation indicating whether the UE 10 supports the NBIFOM function.More specifically, for example, the NBIFOM capability may include“allowed” or “Not allowed”.

Alternatively, the UE NBIFOM capability may be identificationinformation indicating that the UE 10 has the capability of establishingthe first PDN connection. That is, the existence of the UE NBIFOMcapability may mean that the UE 10 has a function of establishing thefirst PDN connection.

In other words, the UE NBIFOM capability may be identificationinformation indicating that the UE 10 supports the NBIFOM function. Thatis, the existence of the UE NBIFOM capability in the storage may meanthat the UE 10 supports the NBIFOM function.

Next, the UE context for each PDN connection will be described. FIG. 12Billustrates an example of the UE context for each PDN connection. Asillustrated in FIG. 12B, the context may include at least an APN, anOperation mode, a Network Policy, a Charging Rule, a PCC Rule, and a QoSRule.

The APN is a label indicating an access destination in the network, inaccordance with the DNS naming convention. The Operation mode isidentification information on a mode that indicates which of the UE andthe network takes an initiative in transmitting and/or receiving data oris allowed to initiate communication control when the PDN connection isthe first PDN connection.

More specifically, for example, an Operation mode in which the UE 10 isallowed to initiate the communication control may be the UE initiatedmode.

Furthermore, an Operation mode that allows the network and/or the PGW 30and/or the PCRF 60 to initiate the communication control may be aNetwork initiated mode.

The Network Policy is a communication control policy on the networkside, and may include the Network allowed mode. Alternatively, the PCRF60 may store the Network allowed mode separately from the NetworkPolicy.

The Charging Rule is a regulation on charging. In accordance with theCharging Rule determined by the PCRF 60, a PCEF performs charging.

The PCC Rule is a regulation relating to control of the Network Policyand Charging Rule. In accordance with the PCC Rule, the PCEF performscommunication control and charging.

The QoS Rule is a regulation relating to QoS of the flow. The QoS Rulemay be associated with the PCC Rule.

FIG. 12C illustrates the UE context for each transfer path and/orbearer. As illustrated in FIG. 12C, the UE context for each transferpath and/or bearer includes at least a Routing Rule.

The Routing Rule indicates an association of a Routing Filter, and aRouting address or Routing access type. Based on this association,whether using a communication path through the 3GPP access network orusing a transfer path through the WLAN access network is determined.

Here, the Routing access type indicates an access network through whichthe flow passes. For example, the Routing access type indicates the 3GPPor the WLAN.

Furthermore, the Routing address indicates an IP address through whichthe flow can pass. For example, the Routing address may be an IP addressof the SGW 35. Alternatively, the Routing address may be an IP addressof the TWAG 74. Alternatively, the Routing address may be an IP addressof a Mobile Access Gateway (MAG).

The Routing Rule may be notified from the UE 10 and/or the TWAG 74and/or the PGW 30. Alternatively, the Routing Rule may be a value thatthe PCRF 60 prestores as a default value. In this case, the PCRF 60 maydetermine the default value of the Routing Rule in accordance with thePCC Rule.

An IP flow may be switched by including an IP header in the RoutingFilter. Alternatively, the flow may be switched for each application byincluding an application ID in the Routing Filter. Alternatively, theRouting Filter may include the TFT.

The Routingu Rule may store multiple rules. Furthermore, the Routingrule may include priority for each rule.

FIG. 12D illustrates an example of the TWAG capability stored in theTWAG 74. In the TWAG capability, identification information (NBIFOMcapability) is stored for each TWAG 74, the information indicatingwhether the capability of establishing the first PDN connection issupported. In other words, the identification information indicateswhether the TWAG 74 supports an NBIFOM function. Specifically, theNBIFOM capability may include “allowed” or “Not allowed”.

Note that the NBIFOM function may be information indicating thepossession of the function of establishing the multi-access PDNconnection.

Alternatively, the NBIFOM capability may be identification informationindicating the possession of the capability of establishing the firstPDN connection. That is, the existence of the NBIFOM capability in thestorage may mean that the TWAG 74 is a gateway capable of establishingthe first PDN connection. In other words, the existence of the NBIFOMcapability in the storage may mean that the TWAG 74 is a gatewaysupporting the NBIFOM function.

As illustrated in FIG. 12D, the NBIFOM capability may be stored inassociation with the TWAG ID that is the identification information onthe TWAG 74. If not associated with the TWAG ID, the NBIFOM capabilitymay mean the capability of the TWAG 74 to be stored.

If the TWAG ID and the NBIFOM capability are stored in association witheach other, the PCRF 60 may store the TWAG capability of multiple TWAGs74.

FIG. 12E illustrates an example of the Network capability stored in thePCRF 60. In the Network capability, the NBIFOM capability is stored foreach network, i.e., for each PGW 30.

Here, the NBIFOM capability denotes identification informationindicating whether the capability of establishing the first PDNconnection is supported for each network. In other words, theidentification information indicates whether the PGW 30 supports theNBIFOM function. More specifically, for example, the NBIFOM capabilitymay include “allowed” or “Not allowed”.

Note that the NBIFOM function may be information indicating thepossession of the function of establishing the multi-access PDNconnection.

Alternatively, the NBIFOM capability may be identification informationindicating the possession of the capability of establishing the firstPDN connection. In other words, the NBIFOM capability may beidentification information indicating that a gateway supports the NBIFOMfunction. That is, the existence of the NBIFOM capability in the storagemay mean that the PGW 30 is a gateway having the function ofestablishing the first PDN connection. In other words, the existence ofthe NBIFOM capability in the storage may mean that the PGW 30 is agateway supporting the NBIFOM function.

1.3. Description of Initial State

An initial state in the present embodiment will be described. Theinitial state in the present embodiment may be a first initial state ora second initial state, both of which will be described later.

Note that the initial state in the present embodiment need not belimited to the first or second initial state.

1.3.1. Description of First Initial State

The first initial state will be described. In the first state, the UE 10has not established the first PDN connection with the core network 90.However, the UE 10 has already established the second PDN connection. Ingreater detail, the UE 10 has not established the first PDN connectionwith a PGW_A 1310. However, the UE 10 has established the second PDNconnection with the PGW_B 1320.

Note that the PGW_A 1310 may be a gateway device selected by using theAPN 1. The PGW_B 1320 may be a gateway device selected by using the APN2. Moreover, the PGW_A 1310 and the PGW_B 1320 may be the PGW 30.Furthermore, the selection of gateway using the APN 1 and/or the APN 2may be performed by the TWAG 74 included and arranged in the accessnetwork B and/or the MME 40 included and arranged in the core network90.

In addition, the gateway device selected by using the APN 1 and thegateway device selected by using the APN 2 may be the same gatewaydevice. In this case, the PGW_A 1310 and the PGW_B 1320 may be the samedevice.

Note that the second PDN connection may be constituted of a transferpath between the UE 10 and the PGW 30 through the access network B.Thus, the first PDN connection may be constituted of a transfer paththat is a combination of a transfer path between the UE 10 and the TWAG74 and a transfer path between the TWAG 74 and the PGW_B 1320. Here, thetransfer path may be a bearer.

As described above, in a first state early stage, the UE 10 may be in astate of being connected to the core network 90 via the access networkB.

Note that the UE 10 need not be connected to the core network 90 via theaccess network A. In other words, the UE 10 need not perform an attachthrough the LTE access network.

Alternatively, the UE 10 may be in a state of being connected to thecore network 90 via the access network A. In this case, the UE 10 mayperform an Attach procedure initiated by the UE 10 to establish a thirdPDN connection.

Note that the third PDN connection may be established with the gatewayselected by using the APN 2. Alternatively, the third PDN connection maybe established with a gateway selected by using an APN different fromthe APN 1 and the APN 2.

The first initial state has been described above; however, the firstinitial state is not limited to the above-described state, and onlyneeds to be a state in which the multi-access PDN connection has notbeen established through the access network B, for example.

1.3.2. Description of Procedure for Leading to First Initial State

A procedure for leading to a first initial state will be described withreference to FIG. 15. In the procedure for leading to the first initialstate, at least an Attach procedure to the core network 90 through theaccess network B, illustrated in (A) of FIG. 15, is performed. The firstinitial state is a state after at least the Attach procedure to the corenetwork 90 through the access network B, illustrated in (A) of FIG. 15,is performed.

Next, details of the Attach procedure to the core network 90 through theaccess network B will be described. The UE 10 first performsauthentication for accessing the access network B and the core network90 and a security association procedure for establishing a securityassociation for transmitting and/or receiving a message with the corenetwork 90 (S1502).

More specifically, the UE 10 performs an authentication procedure foraccessing the TWAG 74 arranged in the access network B and the PGW 30arranged in the core network 90. Upon the completion of theauthentication procedure, the UE 10 performs a procedure forestablishing security associations between the UE 10 and the TWAG 74 andbetween the TWAG 74 and the PGW 30. In the authentication procedure andthe procedure for establishing security associations, the UE 10 maytransmit control information including an Access Point Name (APN) to thecore network 90. The procedures for authentication and for establishingsecurity associations may be performed in accordance with an EAP orother techniques. The UE 10 can obtain the authentication for accessingthe PGW 30 selected by the TWAG 74 using the APN.

Furthermore, the UE 10 may transmit multiple APNs. For example, bytransmitting APN 1 and APN 2, the UE 10 can obtain the authenticationfor accessing a PGW 30 selected by the TWAG 74 using the APN 1 and a PGW30 selected using the APN 2 upon completion of the procedures forauthentication and for establishing a security association.

Upon the establishment of the security association, the UE 10 performs aPDN connectivity procedure for establishing the second PDN connectionwith the core network 90 through the access network B (S1504). Ingreater detail, the UE 10 establishes, via the TWAG 74, the PDNconnection with the PGW_B 1320 arranged in the core network 90.

Specifically, the UE 10 transmits a PDN connectivity request to the TWAG74 and/or the network. The UE 10 may transmit the PDN connectivityrequest including the APN 2.

The TWAG 74 and/or the network receives the PDN connectivity requesttransmitted from the UE 10. The TWAG 74 and/or the network transmits aPDN connectivity accept to the UE 10 upon the reception of the PDNconnectivity request. The TWAG 74 and/or the network may transmit thePDN connectivity accept including APN 2.

The UE 10 receives the PDN connectivity accept transmitted from the TWAG74 and/or the network. The UE 10 transmits a PDN connectivity completeto the TWAG 74 and/or the network based on the PDN connectivity accept.

The TWAG 74 and/or the network receives the PDN connectivity completetransmitted from the UE 10.

1.3.3. Description of Second Initial State

The second initial state will be described. In the second initial state,the UE 10 has not established a connection with the core network 90. Inother words, the UE 10 has not established the first PDN connection andthe second PDN connection with the core network 90. In greater detail,the UE 10 has not established the first PDN connection with the PGW_A1310 included and arranged in the core network 90. Furthermore, the UE10 has not established the second PDN connection with the PGW_B 1320included and arranged in the core network 90.

Note that the PGW_A 1310 may be a gateway device selected by using theAPN 1. The PGW_B 1320 may be a gateway device selected by using the APN2. Furthermore, the selection of gateway using the APN 1 and/or the APN2 may be performed by the TWAG 74 included and arranged in the accessnetwork B and/or the MME 40 included and arranged in the core network90.

As described above, in the second initial state, the UE 10 may have noconnection with the core network 90. In other words, the UE 10 may be ina state of not being connected to the core network 90 through either theaccess network A or access network B. Therefore, the UE 10 may be in astate of not being established any PDN connection.

The second initial state has been described above; however, the secondinitial state is not limited to the above-described state, and onlyneeds to be a state in which the connection to the core network 90through the access network B has not been established, for example.

1.3.4. Description of Procedure for Leading to Second Initial State

A procedure for leading (changing the state) to the second initial statewill be described with reference to FIG. 15. In the procedure forleading (changing the state) to the second initial state, the procedureillustrated in a section (A) of FIG. 15 may not be performed. In otherwords, the second initial state may be a state in which no particularprocedures for making a connection with the core network 90 through theaccess network B is not performed. In other words, the second initialstate may be a state in which the UE 10 makes an initial connection tothe core network 90 through the access network B.

1.3.5. Description of Multi-Access PDN Connectivity EstablishmentProcedure

Next, an establishment procedure of the first PDN connection will bedescribed. Here, the initial state may be the first initial state or thesecond initial state. In the present embodiment, after the establishmentof the initial state, the UE 10 performs a PDN connectivity procedurefor establishing the first PDN connection with the core network 90through the access network B (S1506). In greater detail, the UE 10establishes, via the TWAG 74, the first PDN connection with the PGW_A1310 arranged in the core network 90.

Note that the first PDN connection may be constituted of a path that isa combination of a transfer path between the UE 10 and the TWAG 74 and atransfer path between the TWAG 74 and the PGW_A 1310. Here, the transferpath may be a bearer.

As illustrated in FIG. 15, the procedure for establishing the first PDNconnection may be a PDN connectivity procedure using the APN 1.

A specific example of the PDN connectivity procedure will be describedbelow.

1.4. Examples of PDN Connectivity Procedure

Examples of the PDN connectivity procedure for establishing the firstPDN connection will be described with reference to FIG. 16.

1.4.1. Example of First PDN Connectivity Procedure

An example of the first PDN connectivity procedure will be describedwith reference to FIG. 16.

As illustrated in (B) of FIG. 16, the UE 10 first performs theauthentication and the security association procedure for establishingthe security association. Note that the UE 10 may perform the securityassociation procedure in a case that its initial state is the secondinitial state. In other words, in a case that the initial state is thefirst initial state, the UE 10 need not perform the security associationprocedure. In this way, in the case that the initial state is the firstinitial state, the UE 10 may omit the security association procedurebecause the security association has already been established.

Note that the security association procedure performed by the UE 10 maybe similar to the security association procedure described withreference to (A) of FIG. 15. Therefore, detailed description of theprocedure is omitted.

Next, the UE 10 transmits a PDN connectivity request to the TWAG 74(S2102). The UE 10 may transmit the PDN connectivity request includingat least the PDN connectivity request message identity (PDN connectivityrequest message ID), the Procedure transaction identity (proceduretransaction ID), the Request type (request type), and the PDN type.Furthermore, the UE 10 may include at least first identificationinformation and/or fifth identification information and/or eighthidentification information in the PDN connectivity request. Moreover,the UE 10 may include the access point name (APN) and/or protocolconfiguration options (PCOs) and/or the traffic flow templates (TFTs) inthe PDN connectivity request. Note that the UE 10 may transmit the PCOincluding the first identification information and/or fifthidentification information and/or eighth identification informationand/or the TFT.

Here, the first identification information may be the UE NBIFOMcapability representing that the UE 10 supports the NBIFOM. Note thatthe NBIFOM capability may be information indicating the provision of thefunction of establishing the multi-access PDN connection.

Furthermore, the fifth identification information may be the ModeIndication representing an NBIFOM operation mode for the multi-accessPDN connection whose establishment is requested by the UE 10. Note thatthe UE 10 may include the UE-Initiated mode or the Network-Initiatedmode in the fifth identification information.

As described above, the UE 10 may transmit the fifth identificationinformation to request a mode of the multi-access PDN connection. Inother words, the UE 10 may transmit the fifth identification informationto request the establishment of the multi-access PDN connectioncorresponding to the mode indicated by the fifth identificationinformation. Note that the mode indicated by the fifth identificationinformation may be selected by the UE 10.

Note that, the UE 10 may be configured to transmit the fifthidentification information in a case of requesting the establishment ofthe multi-access PDN connection in the UE-Initiated mode, and may beconfigured not to transmit the fifth identification information in acase of requesting the establishment of the multi-access PDN connectionin the Network-Initiated mode.

Furthermore, the eighth identification information may be informationindicating a default access (Default Assess) in the multi-access PDNconnection. The eighth identification information may be informationindicating the 3GPP access or the WLAN access. The 3GPP access may be anaccess system that is not the WLAN access. More specifically, the 3GPPaccess may be information indicating an access network including theE-UTRAN access, the UTRAN access, and the GERAN access.

Alternatively, the eighth identification information may include moredetailed information. For example, the eighth identification informationmay be one of the E-UTRAN access, the UTRAN access and the GERAN access.

As described above, the UE 10 may transmit the eighth identificationinformation to request a default access for the multi-access PDNconnection. In other words, the UE 10 may transmit the eighthidentification information to request the establishment of themulti-access PDN connection in which the access network indicated by theeighth identification information is used in the default access.

Note that the access network indicated by the eighth identificationinformation may be selected by the UE 10. Furthermore, the UE 10 mayselect the access network indicated by the eighth identificationinformation based on operator policy such as Inter System Routing Policy(ISRP) received from an Access Network Discovery and Selection Function(ANDSF) server. More specifically, the UE 10 may select the accessnetwork indicated by the eighth identification information based onpriority information of the access network of the ISRP received from theANDSF server. For example, since the ISRP indicates that a higherpriority is given to a WLAN, the UE 10 may set information indicatingthe WLAN as the eighth identification information. Note that the UE 10may select the access network indicated by the eighth identificationinformation based on the ISRP, only in a case where the ISRP is valid oractive.

Note that, the UE 10 may be configured to transmit the eighthidentification information when requesting the establishment of themulti-access PDN connection in the UE-Initiated mode, and may beconfigured not to transmit the eighth identification information whenrequesting the establishment of the multi-access PDN connection in theNetwork-Initiated mode.

Furthermore, the UE 10 may be configured to transmit the eighthidentification information in a case where a default bearer has not beenestablished for the multi-access PDN connection, the establishment ofwhich is to be requested, and may be configured not to transmit theeighth identification information in a case where the default bearer hasalready been established for the multi-access PDN connection.

More specifically, the UE 10 may be configured to transmit the eighthidentification information when establishing a new multi-access PDNconnection, and may be configured not to transmit the eighthidentification information when adding a transfer path in a state inwhich the default bearer is established for the multi-access PDNconnection through the LTE access network.

As described above, the UE 10 may make a request for establishing themulti-access PDN connection by transmitting the first identificationinformation and/or the fifth identification information and/or theeighth identification information. In other words, the firstidentification information and/or the fifth identification informationand/or the eighth identification information may be informationindicating the request for establishing a multi-access PDN connection.

The PDN connectivity request message ID may be a message typerepresenting the PDN connectivity request message.

The procedure transaction ID may be information for identifying the PDNconnectivity procedure.

The APN may be an APN, to which the UE 10 requests a connection. Morespecifically, the APN may be the APN 1. The UE 10 may include the APN 1in order to establish the multi-access PDN connection. Here, the APN 1may be an APN that is allowed to establish the multi-access PDNconnection and/or an APN that is allowed to perform communication basedon the NBIFOM.

The request type may be information for identifying the type of the PDNconnectivity procedure to be requested. For example, since the UE 10performs an initial connection by using the APN 1, the request type maybe the type indicating an attach, rather than the type indicating ahandover.

The PDN type may indicate an available IP version. For example, the PDNtype may be IPv4, IPv6, or IPv4v6.

The PCO may be protocol information associated with the PDN connection.Furthermore, the PCO may include identification information on therequest. Note that the UE 10 may transmit the PCO including the firstidentification information and/or fifth identification informationand/or the eighth identification information.

The TFT may be information for identifying an IP flow for performingcommunication by using the PDN connection established in the current PDNconnectivity procedure. Note that the IP flow to be identified may varyfor each application. Thus, the TFT identifies user data of a certainapplication.

More specifically, the TFT may be constituted of a five-tuple, or may beconstituted of identification information such as the application ID.Note that the five-tuple may be constituted of a combination of one ormore of a transmission-source IP address, a transmission-destination IPaddress, a transmission-source port number, a transmission-destinationport number, and a protocol number.

Note that in the present example, when transmitting the PDN connectivityrequest, the UE 10 does not request a certain NBIFOM operation mode, andthus, the UE 10 may transmit the PDN connectivity request withoutincluding the TFT. In other words, when the UE 10 requests theestablishment of the multi-access PDN connection without requesting thecertain NBIFOM operation mode, the UE 10 may transmit the PDNconnectivity request without including the TFT. More specifically, whenthe UE 10 includes the first identification information and/or fifthidentification information and/or eighth identification information, theUE 10 may transmit the PDN connectivity request without including theTFT. Note that conventionally, the UE 10 is capable of transmit the PCOincluding information indicating an IFOM support. Here, the IFOM supportis identification information representing that the IP Flow Mobility(IFOM) is supported. Furthermore, the IFOM is a technique for switchinga communication path of a certain IP flow by using the Dual Stack MobileIPv6 (DSMIPv6) protocol. Thus, including the information indicating theIFOM support in the PCO allows the UE 10 to switch the access networkthrough which the communication of a certain IP flow is performed.

In the present embodiment, in a case where the UE 10 includes the firstidentification information and/or the fifth identification informationand/or the eighth identification information in the PCO, the UE 10 doesnot include the IFOM support. In contrast, in a case where the UE 10includes the IFOM support in the PCO, the UE 10 does not include thefirst identification information and/or the fifth identificationinformation and/or the eighth identification information. As describedabove, it may be possible to not configure both the first identificationinformation and/or fifth identification information and/or eighthidentification information and the IFOM support to be effective toensure a clear distinction between the use of the switching of thecommunication path based on the NBIFOM and the use of the switching ofthe communication path based on the IFOM.

Thus, the UE 10 is capable of establishing either the PDN connectionsupporting the IFOM or the PDN connection supporting the NBIFOM, in theestablishment procedure of a single PDN connection. In other words, thesingle PDN connection is any one of the PDN connection supporting theNBIFOM, the PDN connection supporting the IFOM, or the single-access PDNconnection.

The TWAG 74 receives the PDN connectivity request transmitted from theUE 10. Upon the reception of the PDN connectivity request and/or basedon the first identification information and/or fifth identificationinformation and/or eighth identification information included in the PDNconnectivity request, the TWAG 74 transmits a Create Session Request tothe PGW 30 (S2104).

Upon the reception of the PDN connectivity request and/or based on thefirst identification information and/or fifth identification informationand/or eighth identification information included in the PDNconnectivity request, the TWAG 74 may transmit the Create SessionRequest including at least the first identification information and/orfifth identification information and/or eighth identificationinformation. Furthermore, the TWAG 74 may include the TFT in the CreateSession Request, upon the reception of the TFT transmitted from the UE10.

Note that, the TWAG 74 may be configured to transmit the eighthidentification information in a case of requesting the establishment ofthe multi-access PDN connection in the UE-Initiated mode, and not totransmit the eighth identification information in a case of requestingthe establishment of the multi-access PDN connection in theNetwork-Initiated mode.

Furthermore, the TFT may be information for identifying an IP flow thatperforms communication by using the PDN connection established in thecurrent PDN connectivity procedure. Note that the IP flow to beidentified may vary for each application. Thus, the TFT identifies userdata of a certain application.

More specifically, the TFT may be constituted of a five-tuple, or may beconstituted of identification information such as the application ID.Note that the five-tuple may be constituted of a combination of one ormore of a transmission-source IP address, a transmission-destination IPaddress, a transmission-source port number, a transmission-destinationport number, and a protocol number.

Note that in a case that none of the first identification informationand/or fifth identification information and/or eighth identificationinformation is included in the PDN connectivity request, the TWAG 74 maytransmit the Create Session Request without including the firstidentification information and/or fifth identification informationand/or eighth identification information. Moreover, in the case that thefirst identification information and/or fifth identification informationand/or eighth identification information is not included in the PDNconnectivity request, the TWAG 74 may perform a procedure forestablishing the single-access PDN connection.

The PGW 30 receives the Create Session Request transmitted from the TWAG74. Upon the reception of the Create Session Request, and/or based onthe first identification information and/or fifth identificationinformation and/or eighth identification information included in theCreate Session Request, the PGW 30 may perform an IP-CAN session updateprocedure with the PCRF 60.

Upon the reception of the Create Session Request and/or based on thefirst identification information and/or fifth identification informationand/or eighth identification information included in the Create SessionRequest, the PGW 30 may perform the IP-CAN session update procedureincluding at least the first identification information and/or fifthidentification information and/or eighth identification information.

Note that the PGW 30 may perform the IP-CAN session update procedure tonotify the PCRF 60 of information on the UE 10 and/or TWAG 74.

The PGW 30 may transmit, to the PCRF 60, a control message in the IP-CANsession procedure, including information indicating whether the PDNconnection to be established is the multi-access PDN connection or thesingle-access PDN connection, and/or the first identificationinformation and/or fifth identification information and/or eighthidentification information.

More specifically, when the multi-access PDN connection is to beestablished, the PGW 30 transmits, to the PCRF 60, the informationindicating the access network B, the PDN connection ID, the informationindicating that the PDN connection is the multi-access PDN connection,and the first identification information and/or the fifth identificationinformation and/or the eighth identification information. Alternatively,when the single-access PDN connection is to be established, the PGW 30transmits, to the PCRF 60, the information indicating the access networkB, the PDN connection ID, and the information indicating that the PDNconnection is the single-access PDN connection.

Note that the PDN connection ID may be an ID assigned when the PGW 30establishes the PDN connection in the PDN connectivity procedure, or maybe information for uniquely identifying the PDN connection that the UE10 establishes with the PGW 30.

Furthermore, upon the reception of the first identification informationand/or fifth identification information and/or eighth identificationinformation, the PCRF 60 may transmit, to the PGW 30, a control messagein the IP-CAN session update procedure with the PGW 30, the controlmessage including at least the second identification information and/orseventh identification information and/or ninth identificationinformation. The detailed description of the second identificationinformation and/or the seventh identification information and/or theninth identification information will be described later.

Note that the PCRF 60 may perform the IP-CAN session update procedure tonotify the PGW 30 of the charging information and/or the QoS controlinformation and/or the routing information.

Upon the reception of the Create Session Request or the completion ofthe IP-CAN session update procedure, and/or based on the firstidentification information and/or fifth identification informationand/or eighth identification information included in the Create SessionRequest, and/or based on the second identification information and/orseventh identification information and/or ninth identificationinformation included in the IP-CAN session update procedure, the PGW 30transmits a Create Session Response to the TWAG 74 (S2106).

Upon the reception of the Create Session Request or the completion ofthe IP-CAN session update procedure, and/or based on the firstidentification information and/or fifth identification informationand/or eighth identification information included in the Create SessionRequest, and/or based on the second identification information and/orseventh identification information and/or ninth identificationinformation included in the IP-CAN session update procedure, the PGW 30transmits the Create Session Response including at least the secondidentification information and/or seventh identification informationand/or ninth identification information.

Furthermore, the PGW 30 may include the PDN Address and/or the PDNconnection ID and/or the TFT and/or the bearer identificationinformation identifying the default bearer in the Create SessionResponse.

Note that a method by which the PGW 30 acquires the secondidentification information and/or seventh identification informationand/or ninth identification information is not limited to theabove-described method for acquiring the seventh identificationinformation from the PCRF 60 in the IP-CAN session update procedure, andanother example may be employed. For example, the PGW 30 may create thesecond identification information and/or seventh identificationinformation and/or ninth identification information and transmit theCreate Session Response including the second identification informationand/or seventh identification information and/or ninth identificationinformation, without acquiring from the PCRF 60 in the IP-CAN sessionupdate procedure.

Here, the second identification information may be the NBIFOM capabilityrepresenting that the network supports the NBIFOM. Note that the NBIFOMcapability may be information indicating the provision of the functionof establishing the multi-access PDN connection.

Here, the seventh identification information may be the Allowed Moderepresenting the NBIFOM operation mode that is allowed for themulti-access PDN connection to be established. In other words, theseventh identification information may be an operation mode allowed bythe operator.

As described above, the UE 10 may transmit the seventh identificationinformation to make a notification of the mode of the multi-access PDNconnection. In other words, the UE 10 may transmit the seventhidentification information to permit the establishment of themulti-access PDN connection corresponding to the mode indicated by theseventh identification information. Note that the mode indicated by theseventh identification information may be selected by the PCRF 60 or thePGE 30. Note that the PCRF 60 or the PGE 30 may transmit the modeindicated by the fifth identification information as the seventhidentification information, in a case where the PCRF 60 or the PGE 30allows the establishment of the multi-access PDN connection in the modeindicated by the fifth identification information requested by the UE10.

Note that the PCRF 60 or the PGW 30 may determine the Allowed Mode andthe seventh identification information based on the operator policy. Forexample, a policy that allows the establishment of only the PDNconnection of the UE-Initiated mode, a policy that allows theestablishment of only the PDN connection of the Network-Initiated mode,a policy that allows the establishment of both modes, a policy thatprohibits the establishment of both modes, and the like may be managed.

Note that the PCRF 60 or the PGW 30 may acquire the operator policy fromthe HSS 50 or the like. Alternatively, an operator policy created by anadministrator may be stored.

In addition, for the operator policy, a policy different for eachsubscriber may be managed. Alternatively, a policy different for eachAPN may be managed. For example, for each APN, a different Allowed Modefor the PDN connection to be established may be managed.

On the basis of the Allowed Mode, the PCRF 60 or the PGW 30 may includethe allowed operation mode in the seventh identification information.

In other words, when only the Network-Initiated mode is allowed, thePCRF 60 or the PGW 30 may include the Network-Initiated mode in theseventh identification information. Alternatively, when only theUE-Initiated mode is allowed, the PCRF 60 or the PGW 30 may include theUE-Initiated mode in the seventh identification information.

Note that when both the UE-Initiated mode and the Network-Initiated modeare allowed, the seventh identification information may include both theoperation modes. Alternatively, when both the UE-Initiated mode and theNetwork-Initiated mode are allowed and a default operation mode isconfigured, the seventh identification information may include only thedefault operation mode. Note that which one of the UE-Initiated mode andthe Network-Initiated mode is defined as the default operation mode maybe configured based on the operator policy.

Note that, when none of the operation modes is allowed for establishmentof the PDN connection, the PCRF 60 may transmit, to the PGW 30, thecause information indicating that the requested operation mode is notallowed.

When none of the operation modes is allowed for establishment of the PDNconnection, the PGW 30 need not notify the TWAG 74 of the seventhidentification information.

When none of the operation modes is allowed for establishment of the PDNconnection, the PGW 30 may transmit, to the TWAG 74, the Create SessionResponse including the cause information indicating that the requestedoperation mode is not allowed.

When none of the operation modes is allowed for establishment of the PDNconnection, the PGW 30 may notify the TWAG 74 that there is no allowedoperation.

As described above, on the basis of the Allowed Mode, the PCRF 60 or thePGW 30 may regard an operation mode that is allowed for establishment ofthe PDN connection as the seventh identification information.

Note that when the Network-Initiated mode is not included in the seventhidentification information, the PCRF 60 need not transmit the TFT to thePGW 30.

In other words, note that only when the Network-Initiated mode isincluded in the seventh identification information, the PCRF 60 maytransmit the TFT to the PGW 30.

Note that when the Network-Initiated mode is not included in the seventhidentification information, the PGW 30 need not transmit the TFT to theTWAG 74. Thus, in this case, the PGW 30 need not include the TFT in theCreate Session Response.

In other words, note that only when the Network-Initiated mode isincluded in the seventh identification information, the PGW 30 maytransmit the TFT to the TWAG 74. Thus, in this case, the PGW 30 mayinclude the TFT in the Create Session Response.

The PDN address may be an IP address assigned to the UE 10. For example,the PDN address may be an IPv4 address, or an IPv6 prefix and aninterface ID for constituting an IPv6 address. Here, the PGW 30 mayassign the IP address of the UE 10. Moreover, the PGW 30 may include theIP address assigned to the UE 10 in the PDN address.

Furthermore, the PDN connection ID may be information for uniquelyidentifying the PDN connection established between the UE 10 and the PGW30. The PDN connection ID may be assigned by the PGW 30, or may beassigned by the TWAG 74. In other words, the PGW 30 may assign the PDNconnection ID.

Furthermore, the ninth identification information may be informationindicating a default access (Default Assess) in the multi-access PDNconnection. Note that the ninth identification information may beinformation indicating the 3GPP access or the WLAN access. The 3GPPaccess may be an access system that is not the WLAN access. Morespecifically, the 3GPP access may be information indicating an accessnetwork including the E-UTRAN access, the UTRAN access, and the GERANaccess.

Alternatively, the ninth identification information may include moredetailed information. For example, the ninth identification informationmay be one of E-UTRAN access, UTRAN access and GERAN access.

As described above, the PCRF 60 or the PGE 30 may transmit the ninthidentification information to notify the UE 10 of the default access forthe multi-access PDN connection. In other words, the PCRF 60 or the PGE30 may transmit the ninth identification information to request theestablishment of the multi-access PDN connection in which the accessnetwork indicated by the ninth identification information is used as thedefault access. Note that the access network indicated by the ninthidentification information may be selected by the PCRF 60 or the PGE 30.Note that the PCRF 60 or the PGE 30 may transmit the access networkindicated by the eighth identification information as the ninthidentification information, in a case where the PCRF 60 or the PGE 30allows the establishment of the multi-access PDN connection for thedefault access indicated by the eighth identification informationrequested by the UE 10.

As described above, the establishment of the multi-access PDN connectionis permitted by transmitting the second identification informationand/or the seventh identification information and/or the ninthidentification information. In other words, the second identificationinformation and/or the seventh identification information and/or theninth identification information may be information indicating that themulti-access PDN connection is to be established or establishment of themulti-access PDN connection is permitted.

Note that, the PCRF 60 and the PGW 30 may be configured to transmit theninth identification information in a case where a default bearer hasnot been established for the multi-access PDN connection, theestablishment of which is to be requested, and may be configured not totransmit the ninth identification information in a case where thedefault bearer has already been established for the multi-access PDNconnection.

More specifically, the PCRF 60 and the PGW 30 may be configured totransmit the ninth identification information when establishing a newmulti-access PDN connection, and not to transmit the ninthidentification information when adding a transfer path in a state inwhich the default bearer is established for the multi-access PDNconnection through the LTE access network.

The TWAG 74 receives the Create Session Response transmitted from thePGW 30. Upon the reception of the Create Session Response and/or basedon the second identification information and/or seventh identificationinformation and/or ninth identification information included in theCreate Session Response, the TWAG 74 transmits a PDN connectivity acceptto the UE 10 (S2108). Note that the PDN connectivity accept message maybe any control message indicating that establishment of a PDN connectionis allowed, and may be any Activate default EPS bearer context request.The PDN connectivity accept message may be a response message to the PDNconnectivity request.

Upon the reception of the Create Session Response and/or based on thesecond identification information and/or seventh identificationinformation and/or ninth identification information included in theCreate Session Response, the TWAG 74 may transmit the PDN connectivityaccept including at least a PDN connectivity accept message identity(PDN connectivity accept message ID), the Procedure transaction ID, theAPN, the PDN address (PDN Address), the PDN connection ID, and the userplane connection ID (User Plane Connection ID). Furthermore, the TWAG 74may include at least the second identification information and/orseventh identification information and/or ninth identificationinformation in the PDN connectivity accept. Moreover, the TWAG 74 mayinclude the PCO and/or the Cause and/or the TFT and/or the beareridentification information identifying the default bearer, and/or thePDN connection attribute information, in the PDN connectivity accept.Note that the TWAG 74 may transmit the PCO including the secondidentification information and/or seventh identification informationand/or ninth identification information and/or the TFT.

Here, the PDN connectivity accept message ID may be a message typerepresenting the PDN connectivity accept message.

The APN may be an APN, to which the UE 10 is allowed to connect. Morespecifically, the APN may be the APN 1. The APN 1 may be an APN that isallowed to establish the multi-access PDN connection. The TWAG 74 mayinclude the APN 1 in the PDN connectivity accept.

The PDN address may be an IP address assigned to the UE 10. For example,the PDN address may be an IPv4 address, or an interface ID forconstituting an IPv6 address.

The PDN connection ID may be information for uniquely identifying thePDN connection established between the UE 10 and the PGW 30. The PDNconnection ID may be an ID assigned by the PGW 30, or an ID assigned bythe TWAG 74. In other words, the TWAG 74 may assign the PDN connectionID.

The user plane connection ID is information for identifying a userplane. The user plane is a transfer path used for transferring user datain the PDN connection. The TWAG 74 may assign the user plane connectionID.

The Cause may be information representing that the PDN type of the PDNaddress assigned to the UE 10 is different from the PDN type requestedby the UE 10 in the PDN connectivity request.

Note that the TWAG 74 and/or the PGW 30 may include the secondidentification information and/or the seventh identification informationand/or the ninth identification information in the PCO. However, in acase where the TWAG 74 and/or the PGW 30 includes the secondidentification information and/or the seventh identification informationand/or the ninth identification information in the PCO, the TWAG 74and/or the PGW 30 does not include the IFOM support. In contrast, in acase where the TWAG 74 and/or the PGW 30 includes the IFOM support inthe PCO, the TWAG 74 and/or the PGW 30 does not include the secondidentification information and/or the seventh identification informationand/or the ninth identification information. As described above, it maybe possible to not configure both the second identification informationand/or seventh identification information and/or ninth identificationinformation and the IFOM support to be effective to ensure a cleardistinction between the use of the switching of the communication pathbased on the NBIFOM and the use of the switching of the communicationpath based on the IFOM.

The PDN connection attribute information may be information indicatingthat the PDN connection established in the present PDN connectivityprocedure is the multi-access PDN connection, and/or informationindicating that user data transmitted and/or received by using the PDNconnection established in the PDN connection the present PDNconnectivity procedure is allowed to be transmitted and/or receivedthrough the access network A and the access network B, and/or when thereis only one operation mode indicated by the seventh identificationinformation, information indicating that the PDN connection establishedin the present PDN connectivity procedure is the multi-access PDNconnection of the operation mode indicated by the seventh identificationinformation.

Note that the UE 10 may transmit the PDN connectivity accept messagethat further includes the connectivity type indicating the type of thePDN connection and/or the WLAN offload permission information (WLANoffload acceptablity) indicating whether the WLAN offload can beperformed. Furthermore, the TWAG 74 may transmit the connectivity typeor the WLAN offload permission information including the PDN connectionattribute information.

The UE 10 receives the PDN connectivity accept transmitted from the TWAG74. Upon the reception of the PDN connectivity accept and/or based onthe second identification information and/or seventh identificationinformation and/or ninth identification information included in the PDNconnectivity accept, the UE 10 transmits a PDN connectivity complete tothe TWAG 74 (S2110).

The UE 10 may transmit the PDN connectivity complete including at leasta PDN connectivity complete message ID (PDN connectivity complete), theprocedure transaction ID, and the PDN connection ID.

Furthermore, when multiple INFOM operation modes are included in theseventh identification information, the UE 10 may include at least thefifth identification information in the PDN connectivity complete. Inother words, when multiple INFOM operation modes are allowed, the UE 10may select one of the allowed modes and transmit the fifthidentification information including the selected mode.

Here, the fifth identification information may be the Mode Indicationrepresenting an NBIFOM operation mode for the multi-access PDNconnection whose establishment is requested by the UE 10. Note that theUE 10 may include the UE-Initiated mode or the Network-Initiated mode inthe fifth identification information.

Specifically, when the UE-Initiated mode and the Network-Initiated modeare included in the seventh identification information included in thePDN connectivity accept, the UE 10 may include the UE-Initiated mode orthe Network-Initiated mode in the fifth identification information.

Which of the UE-Initiated mode and the Network-Initiated mode is to beincluded in the fifth identification information may be determined basedon a UE policy. Note that the UE policy may be any informationconfigured for the UE 10. For example, the UE policy may be informationconfigured by a user.

The PDN connectivity complete message ID may be a message typerepresenting the PDN connectivity complete message.

After the first PDN connectivity procedure is completed, the UE 10 andthe PGW 30 establish the first PDN connection of the operation modedetermined based on the operator policy. Alternatively, the UE 10establishes the first PDN connection of an operation mode selected fromthe operation modes allowed based on the operator policy. Note that uponthe reception of the PDN connectivity accept and/or based on the PDNconnection attribute information and/or the seventh identificationinformation and/or the operation mode selected based on the seventhidentification information, the UE 10 may identify the NBIFOM operationmode for the established PDN connection. Upon the establishment of thefirst PDN connection, the UE 10 and the PGW 30 determine a PDNconnection and/or a transfer path, such as an EPS bearer, fortransmitting and/or receiving the IP flow by using the TFT, and transmitand/or receive user data corresponding to the IP flow identified by theTFT. More specifically, the UE 10 and the PGW 30 transmit and/or receivea flow identified by the TFT by using the first PDN connection.

Furthermore, in the establishment of the first PDN connection, the UE 10and the PGW 30 establish a default bearer. The UE 10 and the PGW 30store the identification information of the default bearer establishedin the PDN connectivity procedure and the information identifying theWLA access network in association with each other, in response to thecompletion of the PDN connectivity procedure through the WLAN accessnetwork.

Note that the UE 10 performs data transmission and/or reception usingthe default bearer when the UE 10 does not receive the TFT or transmitsand/or receives the user data not matching the held TFT. In addition,the PGW 30 performs data transmission and/or reception using the defaultbearer when the PGW 30 does not receive the TFT or transmits and/orreceives the user data not matching the held TFT.

In this way, the UE 10 and the PGW 30 establish a multi-access PDNconnection in the PDN connectivity procedure, and establish a defaultbearer for the multi-access PDN connection. Furthermore, the UE 10 andthe PGW 30 are capable of storing a default access for selecting adefault bearer in association with the multi-access PDN connection, in acase where multiple default bearers are established.

Note that in the example of the first PDN connectivity procedure, a casehas been described in which transmission and/or reception of the TFT isincluded in the PDN connectivity procedure; however, the first PDNconnectivity procedure is not limited to this case. The transmissionand/or reception of the TFT may be performed after the multi-access PDNconnection is established.

Therefore, the UE 10 and the TWAG 74 may transmit and/or receive the TFTwithout including the TFT in the PDN connectivity request and/or a PDNconnectivity response (PDN connectivity accept), and establish themulti-access PDN connection. In other words, at a point in time when thePDN connection is established, there may be no IP flow transmittingand/or receiving user data by using the PDN connection. In this case,the UE 10 and the TWAG 74 transmit the TFT after the multi-access PDNconnection is established.

More specifically, when the PDN connection of the UE-Initiated mode isestablished, the UE 10 may transmit the TFT to the TWAG 74. In addition,the TWAG 74 receives the TFT from the UE 10 and transmits the TFT to thePGW 30. Thus, the UE 10 and the PGW 30 are capable of determining a PDNconnection and/or a transfer path such as an EPS bearer for transmittingand/or receiving the IP flow by using the TFT, and are capable oftransmitting and/or receiving user data corresponding to the IP flowidentified by the TFT.

Note that the UE 10 and the PGW 30 perform data transmission and/orreception using the default bearer when the UE 10 and the PGW 30transmit and/or receive the user data not matching the held TFT.

On the other hand, when the PDN connection of the Network-Initiated modeis established, the PGW 30 may transmit the TFT to the TWAG 74. Here,the PGW 30 may receive, from the PCRF 60, the TFT determined on thebasis of the operator policy. In addition, the TWAG 74 receives the TFTfrom the PGW 30 and transmits the TFT to the UE 10. Thus, the UE 10 andthe PGW 30 are capable of determining a PDN connection and/or a transferpath such as an EPS bearer for transmitting and/or receiving the IP flowby using the TFT, and are capable of transmitting and/or receiving userdata corresponding to the IP flow identified by the TFT.

Note that the UE 10 and the PGW 30 perform data transmission andreception using the default bearer when the UE 10 and the PGW 30transmit and/or receive the user data not matching the held TFT.

Furthermore, in the example of the first PDN connectivity procedure, acase has been described in which the UE 10 and the PGW 30 establish thefirst PDN connection of an operation mode selected by the UE 10 from theoperation modes determined based on the operator policy or the operationmodes allowed based on the operator policy; however, the first PDNconnectivity procedure is not limited to this case. The UE 10 may rejectthe establishment of the first PDN connection.

For example, in a case that the UE 10 does not support the operationmode allowed based on the operator policy and/or in a case that theoperation mode allowed based on the operator policy does not comply withthe policy of the UE 10, the UE 10 may reject the establishment of thefirst PDN connection.

In greater detail, the UE 10 may transmit a PDN connectivity reject tothe TWAG 74, upon the reception of the PDN connectivity accept, and/oron the basis of the seventh identification information included in thePDN connectivity accept and/or the PDN connection attribute informationand/or the policy of the UE 10.

The UE 10 may transmit the PDN connectivity reject including at leastone or more of a PDN connectivity reject message identity (PDNconnectivity reject message ID), the procedure transaction ID, and theCause. Furthermore, the UE 10 may include fourth identificationinformation in the PDN connectivity reject. Furthermore, the UE 10 mayinclude the PCO and/or a Tw1 value in the PDN connectivity reject. Notethat the UE 10 may transmit the PCO including the fourth identificationinformation.

The fourth identification information may be information representingthat the UE 10 does not support the operation mode allowed based on theoperator policy and/or information representing that the operation modeallowed based on the operator policy does not comply with the policy ofthe UE 10.

The PDN connectivity reject message ID may be a message typerepresenting a PDN connectivity reject message.

The Cause may be information representing a reason why the PDNconnectivity request is rejected. Here, the UE 10 may notify the UE 10of the fourth identification information included in the Cause.

The Tw1 value may be a value of Tw1 timer included in a case that Causerepresents insufficient resources.

The TWAG 74 may receive the PDN connectivity reject transmitted from theUE 10. Upon the reception of the PDN connectivity reject and/or based onthe fourth identification information included in the PDN connectivityreject, the TWAG 74 may delete the EPS bearer context, held by the TWAG74, relating to the established PDN connection. The TWAG 74 may transmitthe fourth identification information included in the PDN connectivityreject to the PGW 30.

The PGW 30 may receive the fourth identification information transmittedfrom the TWAG 74. Upon the reception of the fourth identificationinformation and/or on the basis of the operator policy, the PGW 30 maydelete the EPS bearer context, held by the PGW 30, relating to theestablished PDN connection.

Furthermore, the PGW 30 may perform the IP-CAN session update procedurewith the PCRF 60, upon the reception of the fourth identificationinformation. The PGW 30 may include the fourth identificationinformation in the IP-CAN session update procedure.

The PCRF 60 may change the operator policy on the basis of the IP-CANsession update procedure. Note that on the basis of the change of theoperator policy, the PGW 30 may delete the EPS bearer context, held bythe PGW 30, relating to the established PDN connection.

1.4.2. Description of State After PDN Connectivity EstablishmentProcedure

Performing the above-described first PDN connectivity procedure leads toa first state and a second state, both of which will be described later.

Note that an initial state in the additional Attach procedure may be thefirst state or the second state. The initial state in the additionalAttach procedure may not be limited to the first or second state.

1.4.3. Description of First State

The first state will be described with reference to FIG. 13. In thefirst state, the UE 10 has established the first PDN connection with thecore network 90. However, the UE 10 has not yet established the secondPDN connection. In greater detail, the UE 10 has established the firstPDN connection with the PGW_A 1310. However, the UE 10 has notestablished the second PDN connection with the PGW_B 1320.

Note that the PGW_A 1310 may be a gateway device selected by using theAPN 1. The PGW_B 1320 may be a gateway device selected by using the APN2. Moreover, the PGW_A 1310 and the PGW_B 1320 may be the PGW 30.Furthermore, the selection of gateway using the APN 1 and/or the APN 2may be performed by the TWAG 74 included and arranged in the accessnetwork B and/or the MME 40 included and arranged in the core network90.

In addition, the gateway device selected by using the APN 1 and thegateway device selected by using the APN 2 may be the same gatewaydevice. In this case, the PGW_A 1310 and the PGW_B 1320 may be the samedevice.

Note that the first PDN connection may be constituted of a transfer pathbetween the UE 10 and the PGW 30 through the access network B. Thus, thefirst PDN connection may be constituted of a transfer path that is acombination of a transfer path between the UE 10 and the TWAG 74 and atransfer path between the TWAG 74 and the PGW_A 1310. Here, the transferpath may be a bearer.

As described above, in the first state, the UE 10 may be in a state inwhich the multi-access PDN connection has been established via theaccess network B. In addition, in the first state, the UE 10 may be in astate of not being connected to the core network 90 via the accessnetwork A.

Note that the UE 10 need not establish the single-access PDN connectionvia the access network B.

Alternatively, the UE 10 may be in a state in which the single-accessPDN connection is established via the access network B. In this case,the UE 10 performs, in the WLAN access network, the Attach procedure orthe PDN connectivity procedure in the single-access PDN connectioninitiated by the UE 10 to establish the third PDN connection.

Note that the third PDN connection may be established with the gatewayselected by using the APN 2. Alternatively, the third PDN connection maybe established with a gateway selected by using an APN different fromthe APN 1 and the APN 2.

The first state has been described above; however, the first state isnot limited to the above-described state, and only needs to be a statein which the multi-access PDN connection has been established throughthe access network B and the PDN connection has not been establishedthrough the access network A, for example.

1.4.4. Description of Second State

The second state will be described with reference to FIG. 14. In thesecond state, the UE 10 has established the first PDN connection withthe core network 90. Furthermore, the UE 10 has established the secondPDN connection with the core network 90. In greater detail, the UE 10has established the first PDN connection with the PGW_A 1310.Furthermore, the UE 10 has established the second PDN connection withthe PGW_B 1320.

Note that the PGW_A 1310 may be a gateway device selected by using theAPN 1. The PGW_B 1320 may be a gateway device selected by using the APN2. Moreover, the PGW_A 1310 and the PGW_B 1320 may be the PGW 30.Furthermore, the selection of gateway using the APN 1 and/or the APN 2may be performed by the TWAG 74 included and arranged in the accessnetwork B and/or the MME 40 included and arranged in the core network90.

In addition, the gateway device selected by using the APN 1 and thegateway device selected by using the APN 2 may be the same gatewaydevice. In this case, the PGW_A 1310 and the PGW_B 1320 may be the samedevice.

Note that the first PDN connection may be constituted of a transfer pathbetween the UE 10 and the PGW 30 through the access network B. Thus, thefirst PDN connection may be constituted of a transfer path that is acombination of a transfer path between the UE 10 and the TWAG 74 and atransfer path between the TWAG 74 and the PGW_B 1320. Here, the transferpath may be a bearer.

In addition, the second PDN connection may be constituted of a transferpath between the UE 10 and the PGW 30 through the access network A.Thus, the second PDN connection may be constituted of a transfer paththat is a combination of a transfer path between the UE 10 and theeNodeB 45, a transfer path between the eNodeB 45 and the SGW 35, and atransfer path between the SGW 35 and the PGW_B 1320. Here, the transferpath may be a bearer.

As described above, in the first state, the UE 10 may be in a state inwhich the multi-access PDN connection has been established via theaccess network B. Furthermore, the UE 10 may be in a state in which thesingle-access PDN connection is established via the access network A.

Note that the UE 10 need not establish the single-access PDN connectionvia the access network B.

Alternatively, the UE 10 may be in a state in which the single-accessPDN connection is established via the access network B. In this case,the UE 10 performs, in the WLAN access network, the Attach procedure orthe PDN connectivity procedure in the single-access PDN connectioninitiated by the UE 10 to establish the third PDN connection.

Note that the third PDN connection may be established with the gatewayselected by using the APN 2. Alternatively, the third PDN connection maybe established with a gateway selected by using an APN different fromthe APN 1 and the APN 2.

The second state has been described above; however, the second state isnot limited to the above-described state, and only needs to be a statein which the multi-access PDN connection has been established throughthe access network B and the single-access PDN connection has beenestablished through the access network A, for example.

1.5. Additional Attach Procedure

An additional Attach procedure will be described below. The Operationmode of the first PDN connection being the Network-initiated mode refersto, in other words, flow switching and/or update of the Routing Rule ofthe PDN connection initiated by the UE 10 being not possible. Incontrast, the PDN connectivity procedure and/or the Attach procedure isinitiated by the UE 10.

Note that the Routing Rule may be information for selecting a transferpath or bearer through which user data is transmitted and/or receivedbased on the TFT held by the UE 10. More specifically, the Routing Rulemay be information in which the TFT and the transfer path or bearer areassociated with each other.

As described above, the second state is a state in which the UE 10establishes the first PDN connection only through the access network B.That is, the transfer path through the LTE access network is notincluded in the first PDN connection. Note that the transfer path may bea bearer and/or a communication path.

Therefore, when the first PDN connection in the second state is in theNetwork-initiated mode, the network and/or the PCRF 60 cannot includethe transfer path through the access network A in the first PDNconnection.

Therefore, based on the state transition to the second state and thefact that the Operation mode is the Network-initiated mode, the UE 10may perform a procedure for establishing the transfer path through theaccess network A.

Moreover, also in a case that the Operation mode of the first PDNconnection in the first state and/or the second state is theUE-initiated mode, the UE 10 may perform a procedure for establishingthe transfer path through the access network A. based on the RoutingRule stored in the UE 10.

Specifically, the UE 10 may perform the procedure for adding a transferpath through the access network A to the first PDN connection in a casethat the Routing Rule of the first PDN connection indicates priority toan LTE access.

More specifically, the UE 10 may perform the procedure for adding atransfer path through the access network A, in a case that the UE 10stores the Routing Rule in which a specific flow and an LTE access areassociated with each other for the first PDN connection.

In other words, the UE 10 does not perform the procedure for adding atransfer path through the access network A to the first PDN connectionin a case that the Routing Rule of the first PDN connection does notindicate priority to an LTE access.

More specifically, the UE 10 does not perform the procedure for adding atransfer path through the access network A in a case that the UE 10 doesnot store the Routing Rule in which a specific flow and an LTE accessare associated with each other for the first PDN connection.

Hereinafter, details of the procedure will be described.

1.5.1. Example of First Additional Attach Procedure

Next, an example of a first additional Attach procedure will bedescribed with reference to FIG. 17. As illustrated in FIG. 17, theinitial state of the present example of procedure is first state(S2302). Note that the procedure for changing the state to the firststate may be similar to the procedure described above, therefore thedetailed description will be omitted.

In the first state, the UE 10 only needs to have established the firstPDN connection with the PGW 30 and/or the network through the accessnetwork A. Specifically, the first state is a state in which the UE 10establishes the first PDN connection, through the TWAG 74, with thePGW_A selected using the APN 1. Note that the first PDN connection maybe the multi-access PDN connection.

The UE 10 performs the Attach procedure through the access network Aupon transition to the first state and establishment of the first PDNconnection in the Network-initiated mode (S2304).

The UE 10 may perform the Attach procedure through the access network Abased on transition to the first state in which the first PDN connectionin the UE-initiated mode is established and based on the Routing Rule.

Specifically, based on the Routing Rule giving priority to an LTEaccess, the UE 10 may perform the Attach procedure through the accessnetwork A.

Specifically, the UE 10 may perform the Attach procedure through theaccess network A in a case that the state is changed to the first statein which the first PDN connection in the UE-initiated mode isestablished and the Routing Rule of the first PDN connection indicatespriority to an LTE access.

More specifically, the UE 10 may perform the Attach procedure throughthe access network A in a case that the state is changed to the firststate in which the first PDN connection in the UE-initiated mode isestablished and the UE 10 stores the Routing Rule in which a specificflow and an LTE access are associated with each other for the first PDNconnection.

In other words, the UE 10 does not perform the Attach procedure throughthe access network A in a case that the Routing Rule of the first PDNconnection does not indicate priority to an LTE access, even if thestate is changed to the first state in which the first PDN connection inthe UE-initiated mode is established.

More specifically, the UE 10 does not perform the Attach procedurethrough the access network A in a case that the UE 10 does not store theRouting Rule in which a specific flow and an LTE access are associatedwith each other for the first PDN connection, even if the state ischanged to the first state in which the first PDN connection in theUE-initiated mode is established.

Note that the UE 10 may transmit the Attach Request including at leastthe APN and/or the PDN connection ID.

The APN may be an APN, to which the UE 10 requests a connection. Morespecifically, the APN may be the APN 2. The UE 10 may include the APN 2in order to establish the single-access PDN connection. Here, the APN 2may be an APN that is not allowed to establish the multi-access PDNconnection and/or an APN that is not allowed to perform communicationbased on the NBIFOM.

That is, the UE 10 may request establishment of a single access PDNconnection, using different APN 2 from the APN 1 acquired from thenetwork when establishing the first PDN connection.

Furthermore, the PDN connection ID may be an ID assigned when the PGW 30establishes the PDN connection in the PDN connectivity procedure, or maybe information for uniquely identifying the PDN connection that the UE10 establishes with the PGW 30.

Note that in the Attach procedure, the UE 10 performs authentication andsecurity association procedure with the MME 40 and the PGW_A and thePGW_B.

In addition, the UE 10 may acquire an APN from the network in responseto the Attach procedure complete.

The APN may be an APN, to which the UE 10 requests a connection. Morespecifically, the APN may be the APN 2. The UE 10 may include the APN 2in order to establish the single-access PDN connection. Here, the APN 2may be an APN that is not allowed to establish the multi-access PDNconnection and/or an APN that is not allowed to perform communicationbased on the NBIFOM.

That is, the UE 10 may establish a single access PDN connection, usingdifferent APN 2 from the APN 1 acquired from the network in response toestablishment of the first PDN connection.

Through above procedures, the UE 10 and the core network 90 changestheir states from the first state to the second state (S2306).

Next, the UE 10 performs the PDN connectivity procedure through theaccess network A upon transition to the second state and establishmentof the first PDN connection in the Network-initiated mode (S2308).

Alternatively, the UE 10 performs the PDN connectivity procedure throughthe access network A, upon transition to the second state and based onthe Routing Rule of the first PDN connection established in theUE-Initiated mode.

Specifically, based on the Routing Rule giving priority to an LTEaccess, the UE 10 may perform the Attach procedure through the accessnetwork A.

Specifically, the UE 10 may perform the procedure for adding a transferpath through the access network A to the first PDN connection in a casethat the state is changed to the second state in which the first PDNconnection in the UE-initiated mode is established and the Routing Ruleof the first PDN connection indicates priority to an LTE access.

More specifically, the UE 10 may perform the procedure for adding atransfer path through the access network A in a case that the state ischanged to the second state in which the first PDN connection in theUE-initiated mode is established and the UE 10 stores the Routing Rulein which a specific flow and an LTE access are associated with eachother for the first PDN connection.

In other words, the UE 10 may not perform the procedure for adding atransfer path through the access network A to the first PDN connectionin a case that the Routing Rule of the first PDN connection does notindicate priority to an LTE access, even when the state is changed tothe second state in which the first PDN connection in the UE-initiatedmode is established.

More specifically, the UE 10 does not perform the procedure for adding atransfer path through the access network A in a case that the UE 10 doesnot store the Routing Rule in which a specific flow and an LTE accessare associated with each other for the first PDN connection, even whenthe state is changed to the second state in which the first PDNconnection in the UE-initiated mode is established.

A PDN connectivity procedure through an access network A will bedescribed with reference to FIG. 18.

The UE 10 first transmits a PDN connectivity request to the MME 40 viathe eNodeB 45 (S2402). The UE 10 may transmit the PDN connectivityrequest including at least the PDN connectivity request message identity(PDN connectivity request message ID), the Procedure transactionidentity (procedure transaction ID), the Request type, the PDN type, theProtocol discriminator, and EPS bearer identity (EPS bearer ID).Furthermore, the UE 10 may include at least first identificationinformation and/or fifth identification information and/or eighthidentification information and/or PDN connection ID in the PDNconnectivity request. Moreover, the UE 10 may include the access pointname (APN) and/or protocol configuration options (PCOs) and/or thetraffic flow templates (TFTs) in the PDN connectivity request. Note thatthe UE 10 may transmit the PCO including the first identificationinformation and/or fifth identification information and/or the eighthidentification information and/or the TFT and/or the PDN connection ID.

Here, the first identification information may be the UE NBIFOMcapability representing that the UE 10 supports the NBIFOM. Note thatthe NBIFOM capability may be information indicating the provision of thefunction of establishing the multi-access PDN connection.

Furthermore, the fifth identification information may be the ModeIndication representing an NBIFOM operation mode for the multi-accessPDN connection whose establishment is requested by the UE 10. Note thatthe UE 10 may include the UE-Initiated mode or the Network-Initiatedmode in the fifth identification information.

As described above, the UE 10 may transmit the fifth identificationinformation to request a mode of the multi-access PDN connection. Inother words, the UE 10 may transmit the fifth identification informationto request the establishment of the multi-access PDN connectioncorresponding to the mode indicated by the fifth identificationinformation. Note that the mode indicated by the fifth identificationinformation may be selected by the UE 10.

Note that, the UE 10 may be configured to transmit the fifthidentification information in a case of requesting the establishment ofthe multi-access PDN connection in the UE-Initiated mode, and may beconfigured not to transmit the fifth identification information in acase of requesting the establishment of the multi-access PDN connectionin the Network-Initiated mode.

Furthermore, the eighth identification information may be informationindicating a default access (Default Assess) in the multi-access PDNconnection. The eighth identification information may be informationindicating the 3GPP access or the WLAN access. The 3GPP access may be anaccess system that is not the WLAN access. More specifically, the 3GPPaccess may be information indicating an access network including theE-UTRAN access, the UTRAN access, and the GERAN access.

Alternatively, the eighth identification information may include moredetailed information. For example, the eighth identification informationmay be one of the E-UTRAN access, the UTRAN access and the GERAN access.

As described above, the UE 10 may transmit the eighth identificationinformation to request a default access for the multi-access PDNconnection. In other words, the UE 10 may transmit the eighthidentification information to request the establishment of themulti-access PDN connection in which the access network indicated by theeighth identification information is used in the default access.

Note that the access network indicated by the eighth identificationinformation may be selected by the UE 10. Furthermore, the UE 10 mayselect the access network indicated by the eighth identificationinformation based on operator policy such as Inter System Routing Policy(ISRP) received from an Access Network Discovery and Selection Function(ANDSF) server. More specifically, the UE 10 may select the accessnetwork indicated by the eighth identification information based onpriority information of the access network of the ISRP received from theANDSF server. For example, since the ISRP indicates that a higherpriority is given to a WLAN, the UE 10 may set information indicatingthe WLAN as the eighth identification information. Note that the UE 10may select the access network indicated by the eighth identificationinformation based on the ISRP, only in a case where the ISRP is valid oractive.

Note that, the UE 10 may be configured to transmit the eighthidentification information when requesting the establishment of themulti-access PDN connection in the UE-Initiated mode, and may beconfigured not to transmit the eighth identification information whenrequesting the establishment of the multi-access PDN connection in theNetwork-Initiated mode.

Furthermore, the UE 10 may be configured to transmit the eighthidentification information in a case where a default bearer has not beenestablished for the multi-access PDN connection, the establishment ofwhich is to be requested, and may be configured not to transmit theeighth identification information in a case where the default bearer hasalready been established for the multi-access PDN connection.

More specifically, the UE 10 may be configured to transmit the eighthidentification information in a case of establishing a new multi-accessPDN connection, and may be configured not to transmit the eighthidentification information in a case of adding a transfer path in astate in which the default bearer is established for the multi-accessPDN connection through the WLAN access network.

As described above, the UE 10 may make a request for establishing themulti-access PDN connection by transmitting the first identificationinformation and/or the fifth identification information and/or theeighth identification information. In other words, the firstidentification information and/or the fifth identification informationand/or the eighth identification information may be informationindicating the request for establishing a multi-access PDN connection.

The PDN connectivity request message ID may be a message typerepresenting the PDN connectivity request message.

The procedure transaction ID may be information for identifying the PDNconnectivity procedure.

The APN may be an APN, to which the UE 10 requests a connection. Morespecifically, the APN may be the APN 1. The UE 10 may include the APN 1in order to establish the multi-access PDN connection. Here, the APN 1may be an APN that is allowed to establish the multi-access PDNconnection and/or an APN that is allowed to perform communication basedon the NBIFOM. Furthermore, the APN may be identification informationidentifying the first PDN connection.

The PDN connection ID may be an ID assigned when the PGW 30 establishesthe PDN connection in the PDN connectivity procedure, or may beinformation for uniquely identifying the PDN connection that the UE 10establishes with the PGW 30. Furthermore, the PDN connection ID may beidentification information identifying the first PDN connection The PDNconnection ID may be associated with the APN.

Note that the UE 10 may identify the first PDN connection by using theAPN and/or the PDN connection ID.

The request type may be information for identifying the type of the PDNconnectivity procedure to be requested. For example, since the UE 10performs an initial connection by using the APN 1, the request type maybe the type indicating an attach, rather than the type indicating ahandover.

The PDN type may indicate an available IP version. For example, the PDNtype may be IPv4, IPv6, or IPv4v6.

The protocol discriminator may be an identifier representing a protocoltype currently used for transmission and/or reception of the PDNconnectivity request.

The EPS bearer ID may be information identifying the EPS bearer. The EPSbearer ID may be assigned by the MME 40.

The PCO may be protocol information associated with the PDN connection.Furthermore, the PCO may include identification information on therequest. Note that the UE 10 may transmit the PCO including the firstidentification information and/or fifth identification informationand/or the eighth identification information.

The TFT may be information for identifying an IP flow for performingcommunication by using the PDN connection established in the current PDNconnectivity procedure. Note that the IP flow to be identified may varyfor each application. Thus, the TFT identifies user data of a certainapplication.

More specifically, the TFT may be constituted of a five-tuple, or may beconstituted of identification information such as the application ID.Note that the five-tuple may be constituted of a combination of one ormore of a transmission-source IP address, a transmission-destination IPaddress, a transmission-source port number, a transmission-destinationport number, and a protocol number.

Note that in the present example, when transmitting the PDN connectivityrequest, the UE 10 does not request a certain NBIFOM operation mode, andthus, the UE 10 may transmit the PDN connectivity request withoutincluding the TFT. In other words, when the UE 10 requests theestablishment of the multi-access PDN connection without requesting thecertain NBIFOM operation mode, the UE 10 may transmit the PDNconnectivity request without including the TFT. More specifically, whenthe UE 10 includes the first identification information and/or fifthidentification information and/or eighth identification information, theUE 10 may transmit the PDN connectivity request without including theTFT.

Note that conventionally, the UE 10 is capable of transmit the PCOincluding information indicating an IFOM support. Here, the IFOM supportis identification information representing that the IP Flow Mobility(IFOM) is supported. Furthermore, the IFOM is a technique for switchinga communication path of a certain IP flow by using between the DualStack Mobile IPv6 (DSMIPv6) protocol. Thus, including the informationindicating the IFOM support in the PCO allows the UE 10 to switch theaccess network through which the communication of a certain IP flow isperformed.

In the present embodiment, in a case where the UE 10 includes the firstidentification information and/or the fifth identification informationand/or the eighth identification information in the PCO, the UE 10 doesnot include the IFOM support. In contrast, in a case where the UE 10includes the IFOM support in the PCO, the UE 10 does not include thefirst identification information and/or the fifth identificationinformation and/or the eighth identification information. As describedabove, it may be possible to not configure both the first identificationinformation and/or fifth identification information and/or eighthidentification information and the IFOM support to be effective toensure a clear distinction between the use of the switching of thecommunication path based on the NBIFOM and the use of the switching ofthe communication path based on the IFOM.

Thus, the UE 10 is capable of establishing either the PDN connectionsupporting the IFOM or the PDN connection supporting the NBIFOM, in theestablishment procedure of a single PDN connection. In other words, thesingle PDN connection is any one of the PDN connection supporting theNBIFOM, the PDN connection supporting the IFOM, or the single-access PDNconnection.

The MME 40 receives the PDN connectivity request transmitted from the UE10. Upon the reception of the PDN connectivity request and/or based onthe first identification information and/or fifth identificationinformation and/or eighth identification information included in the PDNconnectivity request, the MME 40 transmits a Create Session Request tothe SGW 35 (S2404).

Upon the reception of the PDN connectivity request and/or based on thefirst identification information included in the PDN connectivityrequest, the MME 40 may transmit the Create Session Request including atleast the first identification information.

Upon the reception of the PDN connectivity request and/or based on thefifth identification information and/or eighth identificationinformation included in the PDN connectivity request, the MME 40 maytransmit the Create Session Request including at least the fifthidentification information and/or eighth identification information.Furthermore, the MME 40 may include the TFT in the Create SessionRequest, upon the reception of the TFT transmitted from the UE 10.

Furthermore, the MME 40 may include the APN and/or PDN connection ID inthe Create Session Request, upon the reception of the APN and/or PDNconnection ID transmitted from the UE 10. Note that the MME 40 mayidentify the first PDN connection by using the received APN and/or PDNconnection ID.

Furthermore, the TFT may be information for identifying an IP flow thatperforms communication by using the PDN connection established in thecurrent PDN connectivity procedure. Note that the IP flow to beidentified may vary for each application. Thus, the TFT identifies userdata of a certain application.

More specifically, the TFT may be constituted of a five-tuple, or may beconstituted of identification information such as the application ID.Note that the five-tuple may be constituted of a combination of one ormore of a transmission-source IP address, a transmission-destination IPaddress, a transmission-source port number, a transmission-destinationport number, and a protocol number.

Note that in a case that none of the first identification informationand fifth identification information and/or eighth identificationinformation is included in the PDN connectivity request, the MME 40 maytransmit the Create Session Request without including the firstidentification information and/or fifth identification informationand/or eighth identification information. Moreover, in a case that thefirst identification information and/or fifth identification informationand/or eighth identification information is not included in the PDNconnectivity request, the MME 40 may perform a procedure forestablishing the single-access PDN connection.

The SGW 35 receives the Create Session Request transmitted from the MME40. Upon the reception of the PDN connectivity request and/or based onthe first identification information and/or fifth identificationinformation and/or eighth identification information included in the PDNconnectivity request, the SGW 35 transmits the Create Session Request tothe PGW 30 (S2406).

Upon the reception of the session connectivity request and/or based onthe first identification information and/or fifth identificationinformation and/or eighth identification information included in thesession connectivity request, the SGW 35 may transmit the Create SessionRequest including at least the first identification information and/orfifth identification information and/or eighth identificationinformation. Furthermore, the SGW 35 may include the TFT in the CreateSession Request.

Furthermore, the SGW 35 may include the APN and/or PDN connection ID inthe Create Session Request, upon the reception of the APN and/or PDNconnection ID transmitted from the MME 40. Note that the SGW 35 mayidentify the first PDN connection by using the received APN and/or PDNconnection ID.

Furthermore, the TFT may be information for identifying an IP flow thatperforms communication by using the PDN connection established in thecurrent PDN connectivity procedure. Note that the IP flow to beidentified may vary for each application. Thus, the TFT identifies userdata of a certain application.

More specifically, the TFT may be constituted of a five-tuple, or may beconstituted of identification information such as the application ID.Note that the five-tuple may be constituted of a combination of one ormore of a transmission-source IP address, a transmission-destination IPaddress, a transmission-source port number, a transmission-destinationport number, and a protocol number.

Note that in a case that none of the first identification informationand the fifth identification information and/or eighth identificationinformation is included in the create session request, the SGW 35 maytransmit the Create Session Request without including the firstidentification information and/or fifth identification informationand/or eighth identification information. Moreover, in a case that thefirst identification information and/or fifth identification informationand/or eighth identification information is not included in the PDNconnectivity request, the MME 40 may perform a procedure forestablishing the single-access PDN connection.

The PGW 30 receives the Create Session Request transmitted from the SGW35. Upon the reception of the Create Session Request, and/or based onthe first identification information and/or fifth identificationinformation and/or eighth identification information included in theCreate Session Request, the PGW 30 may perform an IP-CAN session updateprocedure with the PCRF 60 (S2408).

Upon the reception of the Create Session Request and/or based on thefirst identification information and/or fifth identification informationand/or eighth identification information included in the Create SessionRequest, the PGW 30 may perform the IP-CAN session update procedureincluding at least the first identification information and/or fifthidentification information and/or eighth identification information.

Furthermore, the PGW 30 may identify the first PDN connection by usingthe received APN and/or PDN connection ID, upon the reception of the APNand/or PDN connection ID transmitted from the SGW 35.

Note that the PGW 30 may perform the IP-CAN session update procedure tonotify the PCRF 60 of information on the UE 10 and/or the eNodeB 45and/or the MME 40 and/or the SGW 35.

The PGW 30 may transmit, to the PCRF 60, a control message in the IP-CANsession procedure, including information indicating whether the PDNconnection to be established is the multi-access PDN connection or thesingle-access PDN connection, and/or the first identificationinformation and/or fifth identification information and/or eighthidentification information.

More specifically, when the multi-access PDN connection is to beestablished, the PGW 30 transmits, to the PCRF 60, the informationindicating the access network A, the PDN connection ID, the informationindicating that the PDN connection is the multi-access PDN connection,and the first identification information and/or the fifth identificationinformation and/or the eighth identification information. Alternatively,when the single-access PDN connection is to be established, the PGW 30transmits, to the PCRF 60, the information indicating the access networkA, the PDN connection ID, and the information indicating that the PDNconnection is the single-access PDN connection.

Note that the PDN connection ID may be an ID assigned when the PGW 30establishes the PDN connection in the PDN connectivity procedure, or maybe information for uniquely identifying the PDN connection that the UE10 establishes with the PGW 30.

Furthermore, upon the reception of the first identification informationand/or fifth identification information and/or eighth identificationinformation, the PCRF 60 may transmit, to the PGW 30, a control messagein the IP-CAN session update procedure with the PGW 30, the controlmessage including at least the second identification information and/orseventh identification information and/or ninth identificationinformation. The detailed description of the second identificationinformation and/or the seventh identification information and/or theninth identification information will be described later.

Note that the PCRF 60 may perform the IP-CAN session update procedure tonotify the PGW 30 of the charging information and/or the QoS controlinformation and/or the routing information.

Upon the reception of the Create Session Request or the completion ofthe IP-CAN session update procedure, and/or based on the firstidentification information and/or fifth identification informationand/or eighth identification information included in the Create SessionRequest, and/or based on the second identification information and/orseventh identification information and/or ninth identificationinformation included in the IP-CAN session update procedure, the PGW 30transmits a Create Session Response to the SGW 35 (S2410).

Upon the reception of the Create Session Request or the completion ofthe IP-CAN session update procedure, and/or based on the firstidentification information and/or fifth identification informationand/or eighth identification information included in the Create SessionRequest, and/or based on the second identification information and/orseventh identification information and/or ninth identificationinformation included in the IP-CAN session update procedure, the PGW 30transmits the Create Session Response including at least the secondidentification information and/or seventh identification informationand/or ninth identification information.

Furthermore, the PGW 30 may include the PDN Address and/or the PDNconnection ID and/or the TFT and/or the bearer identificationinformation identifying the default bearer in the Create SessionResponse.

Note that a method by which the PGW 30 acquires the secondidentification information and/or seventh identification informationand/or ninth identification information is not limited to theabove-described method for acquiring the seventh identificationinformation from the PCRF 60 in the IP-CAN session update procedure, andanother example may be employed. For example, the PGW 30 may create thesecond identification information and/or seventh identificationinformation and/or ninth identification information and transmit theCreate Session Response including the second identification informationand/or seventh identification information and/or ninth identificationinformation, without acquiring from the PCRF 60 in the IP-CAN sessionupdate procedure.

Here, the second identification information may be the NBIFOM capabilityrepresenting that the network supports the NBIFOM. Note that the NBIFOMcapability may be information indicating the provision of the functionof establishing the multi-access PDN connection.

Here, the seventh identification information may be the Allowed Moderepresenting the NBIFOM operation mode that is allowed for themulti-access PDN connection to be established. In other words, theseventh identification information may be an operation mode allowed bythe operator.

As described above, the UE 10 may transmit the seventh identificationinformation to make a notification of the mode of the multi-access PDNconnection. In other words, the UE 10 may transmit the seventhidentification information to permit the establishment of themulti-access PDN connection corresponding to the mode indicated by theseventh identification information. Note that the mode indicated by theseventh identification information may be selected by the PCRF 60 or thePGE 30. Note that the PCRF 60 or the PGE 30 may transmit the modeindicated by the fifth identification information as the seventhidentification information, in a case where the PCRF 60 or the PGE 30allows the establishment of the multi-access PDN connection in the modeindicated by the fifth identification information requested by the UE10.

Note that the PCRF 60 or the PGW 30 may determine the Allowed Mode andthe seventh identification information based on the operator policy. Forexample, a policy that allows the establishment of only the PDNconnection of the UE-Initiated mode, a policy that allows theestablishment of only the PDN connection of the Network-Initiated mode,a policy that allows the establishment of both modes, a policy thatprohibits the establishment of both modes, and the like may be managed.

Note that the PCRF 60 or the PGW 30 may acquire the operator policy fromthe HSS 50 or the like. Alternatively, an operator policy created by anadministrator may be stored.

In addition, for the operator policy, a policy different for eachsubscriber may be managed. Alternatively, a policy different for eachAPN may be managed. For example, for each APN, a different Allowed Modefor the PDN connection to be established may be managed.

On the basis of the Allowed Mode, the PCRF 60 or the PGW 30 may includethe allowed operation mode in the seventh identification information.

In other words, when only the Network-Initiated mode is allowed, thePCRF 60 or the PGW 30 may include the Network-Initiated mode in theseventh identification information. Alternatively, when only theUE-Initiated mode is allowed, the PCRF 60 or the PGW 30 may include theUE-Initiated mode in the seventh identification information.

Note that when both the UE-Initiated mode and the Network-Initiated modeare allowed, the seventh identification information may include both theoperation modes. Alternatively, when both the UE-Initiated mode and theNetwork-Initiated mode are allowed and a default operation mode isconfigured, the seventh identification information may include only thedefault operation mode. Note that which one of the UE-Initiated mode andthe Network-Initiated mode is defined as the default operation mode maybe configured based on the operator policy.

Note that, when none of the operation modes is allowed for establishmentof the PDN connection, the PCRF 60 may transmit, to the PGW 30, thecause information indicating that the requested operation mode is notallowed.

In a case that none of the operation modes is allowed for establishmentof the PDN connection, the PGW 30 need not notify the MME 40 of theseventh identification information via the SGW 35.

In a case that none of the operation modes is allowed for establishmentof the PDN connection, the PGW 30 may transmit, to the MME 40 via theSGW 35, the Create Session Response including the cause informationindicating that the Requested Operation Mode is not allowed.

In a case that none of the operation modes is allowed for establishmentof the PDN connection, the PGW 30 may notify the MME 40 that there is noallowed operation via the SGW 35.

As described above, on the basis of the Allowed Mode, the PCRF 60 or thePGW 30 may regard an operation mode that is allowed for establishment ofthe PDN connection as the seventh identification information.

Note that when the Network-Initiated mode is not included in the seventhidentification information, the PCRF 60 need not transmit the TFT to thePGW 30.

In other words, note that only when the Network-Initiated mode isincluded in the seventh identification information, the PCRF 60 maytransmit the TFT to the PGW 30.

Note that in a case that the Network-Initiated mode is not included inthe seventh identification information, the PGW 30 need not transmit theTFT to the MME 40 via the SGW 35. Thus, in this case, the PGW 30 neednot include either the TFT or the PDN address in the Create SessionResponse.

Note that, in other words, only in a case that the Network-Initiatedmode is included in the seventh identification information, the PGW 30may transmit the TFT to the MME 40 via the SGW 35. Thus, in this case,the PGW 30 may include the TFT and the PDN address (PDN Address) in theCreate Session Response.

The PDN address may be an IP address assigned to the UE 10. For example,the PDN address may be an IPv4 address, or an IPv6 prefix and aninterface ID for constituting an IPv6 address. Here, the PGW 30 mayassign the IP address of the UE 10. Moreover, the PGW 30 may include theIP address assigned to the UE 10 in the PDN address.

Furthermore, the PDN connection ID may be information for uniquelyidentifying the PDN connection established between the UE 10 and the PGW30. The PDN connection ID may be assigned by the PGW 30, or may beassigned by the MME 40. In other words, the PGW 30 may assign the PDNconnection ID.

Furthermore, the ninth identification information may be informationindicating a default access (Default Assess) in the multi-access PDNconnection. Note that the ninth identification information may beinformation indicating the 3GPP access or the WLAN access. The 3GPPaccess may be an access system that is not the WLAN access. Morespecifically, the 3GPP access may be information indicating an accessnetwork including the E-UTRAN access, the UTRAN access, and the GERANaccess.

Alternatively, the ninth identification information may include moredetailed information. For example, the ninth identification informationmay be one of E-UTRAN access, UTRAN access and GERAN access.

As described above, the PCRF 60 or the PGE 30 may transmit the ninthidentification information to notify the UE 10 of the default access forthe multi-access PDN connection. In other words, the PCRF 60 or the PGE30 may transmit the ninth identification information to request theestablishment of the multi-access PDN connection in which the accessnetwork indicated by the ninth identification information is used as thedefault access. Note that the access network indicated by the ninthidentification information may be selected by the PCRF 60 or the PGE 30.Note that the PCRF 60 or the PGE 30 may transmit the access networkindicated by the eighth identification information as the ninthidentification information, in a case where the PCRF 60 or the PGE 30allows the establishment of the multi-access PDN connection for thedefault access indicated by the eighth identification informationrequested by the UE 10.

As described above, the establishment of the multi-access PDN connectionis permitted by transmitting the second identification informationand/or the seventh identification information and/or the ninthidentification information. In other words, the second identificationinformation and/or the seventh identification information and/or theninth identification information may be information indicating that themulti-access PDN connection is to be established or establishment of themulti-access PDN connection is permitted.

Note that, the PCRF 60 and the PGW 30 may be configured to transmit theninth identification information in a case where a default bearer hasnot been established for the multi-access PDN connection, theestablishment of which is to be requested, and may be configured not totransmit the ninth identification information in a case where thedefault bearer has already been established for the multi-access PDNconnection.

More specifically, the PCRF 60 and the PGW 30 may be configured totransmit the ninth identification information when establishing a newmulti-access PDN connection, and not to transmit the ninthidentification information when adding a transfer path in a state inwhich the default bearer is established for the multi-access PDNconnection through the LTE access network.

The SGW 35 receives the Create Session Response transmitted from the PGW30. Upon the reception of the Create Session Response and/or based onthe second identification information and/or seventh identificationinformation and/or ninth identification information included in theCreate Session Response, the SGW 35 transmits the Create SessionResponse to the MME 40 (S2412).

Upon the reception of the Create Session Response and/or based on thesecond identification information and/or seventh identificationinformation and/or ninth identification information included in theCreate Session Response, the SGW 35 may transmit the Create SessionResponse including at least the second identification information and/orseventh identification information and/or ninth identificationinformation.

Furthermore, the SGW 35 may include the PDN Address and/or the PDNconnection ID and/or the TFT in the Request Session Response.

The MME 40 receives the Create Session Response transmitted from the SGW35. Upon the reception of the Create Session Response and/or based onthe second identification information and/or seventh identificationinformation and/or ninth identification information included in theCreate Session Response, the MME 40 transmit the Activate default EPSbearer context request to the eNodeB 45 (S2414).

Upon the reception of the Create Session Response and/or based on thesecond identification information and/or seventh identificationinformation and/or ninth identification information included in theCreate Session Response, the MME 40 may transmit at least an Activatedefault EPS bearer context request message identity (Activate defaultEPS bearer context request message ID), a Procedure transaction ID, anAPN, a PDN Address, a protocol discriminator, an EPS bearer ID, and EPSQoS included in the Activate default EPS bearer context request. Uponthe reception of the Create Session Response and/or based on the secondidentification information and/or seventh identification informationand/or ninth identification information included in the Create SessionResponse, the MME 40 may further include at least the secondidentification information and/or seventh identification informationand/or ninth identification information in the Activate default EPSbearer context request. Moreover, the MME 40 may include the PCO and/orthe ESM Cause and/or the TFT and/or the bearer identificationinformation identifying the default bearer, and/or the PDN connection IDand/or the PDN connection attribute information, in the Activate defaultEPS bearer context request. Note that the MME 40 may transmit the PCOincluding the second identification information and/or seventhidentification information and/or ninth identification informationand/or the TFT and/or the bearer identification information identifyingthe default bearer and/or the PDN connection ID.

Here, the Activate default EPS bearer context request message ID may bea message type representing the Activate default EPS bearer contextrequest message.

The APN may be an APN, to which the UE 10 is allowed to connect. Morespecifically, the APN may be the APN 1. The APN 1 may be an APN that isallowed to establish the multi-access PDN connection. The MME 40 mayinclude the APN 1 in the Activate default EPS bearer context request.

The PDN address may be an IP address assigned to the UE 10. For example,the PDN address may be an IPv4 address, or an interface ID forconstituting an IPv6 address.

The EPS QoS may indicate a state representing QoS of an EPS bearer.

The PDN connection attribute information may be information indicatingthat the PDN connection established in the present PDN connectivityprocedure is the multi-access PDN connection, and/or informationindicating that user data transmitted and/or received by using the PDNconnection established in the PDN connection the present PDNconnectivity procedure is allowed to be transmitted and/or receivedthrough the access network A and the access network B, and/orinformation indicating that the PDN connection established in thepresent PDN connectivity procedure is the multi-access PDN connection ofthe operation mode indicated by the seventh identification information.

Note that the UE 10 may transmit the Activate default EPS bearer contextrequest message that further includes the connectivity type indicatingthe type of the PDN connection and/or the WLAN offload permissioninformation (WLAN offload acceptablity) indicating whether the WLANoffload can be performed. Furthermore, the MME 40 may transmit theconnectivity type or the WLAN offload permission information includingthe PDN connection attribute information.

ESM Cause may be information representing that the PDN type of the PDNaddress assigned to the UE 10 is different from the PDN type requestedby the UE 10 in the PDN connectivity request.

Note that the MME 40 and/or the PGW 30 may include the secondidentification information and/or the seventh identification informationand/or the ninth identification information in the PCO. However, in acase where the MME 40 and/or the PGW 30 includes the secondidentification information and/or the seventh identification informationand/or the ninth identification information in the PCO, the MME 40and/or the PGW 30 does not include the IFOM support. In contrast, in acase where the MME 40 and/or the PGW 30 includes the IFOM support in thePCO, the MME 40 and/or the PGW 30 does not include the secondidentification information and/or the seventh identification informationand/or the ninth identification information. As described above, it maybe possible to not configure both the second identification informationand/or seventh identification information and/or ninth identificationinformation and the IFOM support to be effective to ensure a cleardistinction between the use of the switching of the communication pathbased on the NBIFOM and the use of the switching of the communicationpath based on the IFOM.

The eNodeB 45 receives the Activate default EPS bearer context requesttransmitted from the MME 40. Upon the reception of the Activate defaultEPS bearer context request, the eNodeB 45 transfers the Activate defaultEPS bearer context request to the UE 10.

The eNodeB 45 may transmit at least an RRC connection configurationrequest (RRC Connection Reconfiguration) to the UE 10 with an Activatedefault EPS bearer context request (S2416).

The UE 10 receives the RRC connection configuration request transmittedfrom the eNodeB 45. Furthermore, the UE 10 receives the Activate defaultEPS bearer context request transmitted from the MME 40 and transferredby the eNodeB 45.

Upon the reception of the RRC connection configuration request, the UE10 transmits the RRC connection configuration complete (RRC ConnectionReconfiguration Complete) to the eNodeB 45 (S2418).

The eNodeB 45 receives the RRC connection configuration completetransmitted from the UE 10. The eNodeB 45 transmits bearer configurationto the MME 40 in response to the RRC connection configuration complete.

The MME 40 receives the bearer configuration transmitted from the eNodeB45 (S2420).

Upon the reception of the Activate default EPS bearer context requestand/or based on the second identification information and/or seventhidentification information and/or ninth identification informationincluded in the Activate default EPS bearer context request, the UE 10transmits an Activate default EPS bearer context accept or an Activatedefault EPS bearer context reject to the MME 40 (S2422) (S2424).

The UE 10 may transmit at least an Activate default EPS bearer contextaccept message identity (Activate default EPS bearer context acceptmessage ID), a procedure transaction ID, a protocol discriminator, andan EPS bearer ID included in the Activate default EPS bearer contextaccept.

The UE 10 may transmit at least an Activate default EPS bearer contextreject message identity (Activate default EPS bearer context rejectmessage ID), a Procedure transaction ID, a protocol discriminator, anEPS bearer ID, and an ESM Cause included in the Activate default EPSbearer context reject.

Furthermore, the UE 10 may include the PCO in the Activate default EPSbearer context accept and/or the Activate default EPS bearer contextreject.

Furthermore, in a case that multiple INFOM operation modes are includedin the seventh identification information, the UE 10 may include atleast the fifth identification information in the Activate default EPSbearer context accept and/or the Activate default EPS bearer contextreject. In other words, when multiple INFOM operation modes are allowed,the UE 10 may select one of the allowed modes and transmit the fifthidentification information including the selected mode.

Here, the fifth identification information may be the Mode Indicationrepresenting an NBIFOM operation mode for the multi-access PDNconnection whose establishment is requested by the UE 10. Note that theUE 10 may include the UE-Initiated mode or the Network-Initiated mode inthe fifth identification information.

Specifically, in a case that the UE-Initiated mode and theNetwork-Initiated mode are included in the seventh identificationinformation included in the Activate default EPS bearer context request,the UE 10 may include the UE-Initiated mode or the Network-Initiatedmode in the fifth identification information.

Which of the UE-Initiated mode and the Network-Initiated mode is to beincluded in the fifth identification information may be determined basedon the UE policy. Note that the UE policy may be any informationconfigured for the UE 10. For example, the UE policy may be informationconfigured by a user.

Here, the Activate default EPS bearer context accept message ID may be amessage type representing the Activate default EPS bearer context acceptmessage.

The Activate default EPS bearer context reject message ID may be amessage type representing the Activate default EPS bearer context rejectmessage.

The ESM Cause may be information representing a reason of rejecting theActivate default EPS bearer context request.

Thus, the UE 10 completes the additional Attach procedure.

That is, the UE 10 can establish an additional transfer path through theLTE access network A, based on the transition to the first state andbased on the Operation mode of the first PDN connection.

Specifically, the UE 10 can perform the Attach procedure and the PDNconnectivity procedure on the LTE access network A to establish theadditional transfer path via the eNB 45, based on the transition to thefirst state and based on the fact that the first PDN connection is inthe Network-initiated mode. Note that the transfer path may be a bearerand/or a communication path.

More specifically, the UE 10 performs the Attach procedure, establishesthe second PDN connection between the PGW_B selected using the APN 2 andthe UE 10, and then performs the PDN connectivity procedure, so that atransfer path through the LTE access network can be added to the firstPDN connection between the PGW_A selected using the APN 1 and the UE 10.Note that the transfer path may be a bearer and/or a communication path.That is, in the state in which a default bearer through the WLAN isestablished, a default bearer through the LTE access network for thefirst PDN connection can be further established.

Alternatively, the UE 10 can perform the Attach procedure and the PDNconnectivity procedure on the LTE access network A to establish theadditional transfer path via the eNB 45, based on transition to thefirst state and based on the Routing Rule of the first PDN connectionestablished in the UE-initiated mode. Note that the transfer path may bea bearer and/or a communication path.

Specifically, the UE 10 performs the Attach procedure, establishes thesecond PDN connection between the PGW_B selected using the APN 2 and theUE 10, and then performs the PDN connectivity procedure, so that atransfer path through the LTE access network can be added to the firstPDN connectivity between the PGW_A selected using the APN 1 and the UE10. Note that the transfer path may be a bearer and/or a communicationpath.

Furthermore, the UE 10 can establish an additional transfer path throughthe LTE access network A, based on the transition to the second stateand based on the Operation mode of the first PDN connection.

Specifically, the UE 10 can perform the PDN connectivity procedure onthe LTE access network A to establish the additional transfer path viathe eNB 45, based on the transition to the second state and based on thefact that the first PDN connection is in the Network-initiated mode.Note that the transfer path may be a bearer and/or a communication path.

More specifically, the UE 10 performs the PDN connectivity procedure, sothat a transfer path through the LTE access network can be added to thefirst PDN connectivity between the PGW_A selected using the APN 1 andthe UE 10. Note that the transfer path may be a bearer and/or acommunication path.

Alternatively, the UE 10 can perform the PDN connectivity procedure onthe LTE access network A to establish the additional transfer path viathe eNB 45, based on transition to the second state and based on theRouting Rule of the first PDN connection established in the UE-initiatedmode. Note that the transfer path may be a bearer and/or a communicationpath.

Specifically, the UE 10 performs the PDN connectivity procedure, so thata transfer path through the LTE access network can be added to the firstPDN connectivity between the PGW_A selected using the APN 1 and the UE10. Note that the transfer path may be a bearer and/or a communicationpath.

In this way, with respect to the first PDN connection, the UE 10 and thePGW 30 establish a new default bearer. The UE 10 and the PGW 30 storethe identification information of the default bearer established in thePDN connectivity procedure and the information identifying the LTEaccess network in association with each other, in response to completionof the PDN connectivity procedure through the LTE access network.Furthermore, the information identifying the LTE access network may beinformation indicating a 3GPP access or information indicating anE-UTRAN access.

Note that the UE 10 performs data transmission and/or reception usingthe default bearer when the UE 10 does not receive the TFT or transmitsand/or receives the user data not matching the held TFT. When multipledefault bearers are established, the UE 10 is capable of selecting adefault bearer for transmitting and/or receiving data based on thedefault access, and is capable of transmitting and/or receiving data byusing the selected default bearer.

Here, the default access may be default access indicated by the ninthidentification information. In a case where the UE 10 does not receivethe ninth identification information at the time of establishing thesecond default bearer for the first PDN connection, the UE 10 may selectthe default access based on the ninth identification informationreceived at the time of establishing the first default bearer for thefirst PDN connection, and transmit and/or receive data using theselected default bearer.

Furthermore, the PGW 30 performs data transmission and/or receptionusing the default bearer when the PGW 30 does not receive the TFT ortransmits and/or receives the user data not matching the held TFT. Whenthe PGW 30 establishes multiple default bearers with the UE 10, the PGW30 is capable of selecting a default bearer for transmitting and/orreceiving data based on the default access, and is capable oftransmitting and/or receiving data by using the selected default bearer.Here, the default access may be default access indicated by the ninthidentification information.

Here, the default access may be default access indicated by the ninthidentification information. In a case where the PGW 30 does not transmitthe ninth identification information at the time of establishing thesecond default bearer for the first PDN connection, the PGW 30 mayselect the default access based on the ninth identification informationtransmitted at the time of establishing the first default bearer for thefirst PDN connection, and transmit and/or receive data using theselected default bearer.

In this way, in a case where the UE 10 and the PGE 30 are capable ofacquiring the default access in the state where the second defaultbearer is not established, the PDN connectivity establishment procedurefor establishing the second unnecessary default bearer is eliminated.For example, in a case that the communication path through the LTEaccess network is established by the additional PDN connectionprocedure, there may be a case in which no user data that selects thecommunication path through the LTE access network exists, and thecommunication path is not used, depending on the Routing Rule based onthe TFT or the like. Learning a default access beforehand eliminates theestablishment of such an unnecessary communication path between the UE10 and the PGW 30, and therefore reduces transmission and/or receptionof control messages for unnecessary communication path establishment,consumption of the resources for the communication path, and the like.

In this way, if the UE 10 and the PGE 30 can acquire the default accessin the state where the second default bearer is not established, the UE10 can determine whether performing the PDN connection establishmentprocedure for establishing a new default bearer for the multi-access PDNconnection based on the information on the default access, when the UE10 is newly located in a serving area of an LTE access network.

For example, in a case that the default access indicates a WLAN network,the multi-access access PDN connection is in the UE-Initiated mode, andthe Routing Rule does not include user data to which priority is givento communicate by the communication path through the LTE, it is notnecessary to immediately perform the additional transfer pathestablishment procedure for establishing the default bearer through theLTE.

2. Second Embodiment

Hereinafter, a radio communication technology according to an embodimentof the present invention will be described in detail with reference tothe drawings.

2.1. System Overview

The mobile communication system in the present embodiment may be similarto that in the first embodiment. Therefore, the overview of the mobilecommunication system is similar to the mobile communication systemdescribed in Chapter 2.1 of the first embodiment with reference to FIG.1, and detailed description is omitted.

In the present embodiment, the UE 10 is capable of establishing a firstPDN connection and/or a second PDN connection.

Furthermore, in the present embodiment, the NBIFOM is a technology thatallows establishment of a multi-access PDN connection.

Furthermore, in the present embodiment, the multi-access PDN connectiondenotes a PDN connection capable of accommodating, in one PDNconnection, a transfer path and/or a bearer over a 3GPP access and/or aWLAN access. In other words, the multi-access PDN connection canaccommodate a transfer path through the 3GPP access and a transfer paththrough the WLAN access in combination. Note that the multi-access PDNconnection may be a PDN connection accommodating only a bearer throughthe 3GPP access or may be a PDN connection accommodating only a transferpath through the WLAN access. In other words, the multi-access PDNconnection denotes a PDN connection capable of constituting one ormultiple transfer paths.

Note that in the present embodiment, unlike the first embodiment, themulti-access PDN connection may be a PDN connection established based onthe NBIFOM or a PDN connection established based on the IP Flow Mobility(IFOM). Thus, in the present embodiment, the multi-access PDN connectionmay be either the multi-access PDN connection corresponding to the PDNconnection in which a transfer path of a certain flow is selectablebased on the NBIFOM or the multi-access PDN connection corresponding tothe PDN connection in which a transfer path of a certain flow isselectable based on the IFOM.

Note that the IFOM is a technology for switching a communication path ofa certain IP flow by using the Dual Stack Mobile IPv6 (DSMIPv6)protocol. On the other hand, the NBIFOM is a technology for switching acommunication path of a certain IP flow by using a network-basedmobility management protocol such as a general packet radio systemtunneling protocol (GTP) and a proxy mobile IP (PMIP). Furthermore, thefirst PDN connection may be the above-described multi-access PDNconnection.

In detail, the first PDN connection is a PDN connection in which, as onePDN connection, a communication path EPS bearer through the accessnetwork A and a communication path including a GTP/PMIPv6 tunnel throughthe access network B can be used. That is, such a PDN connection enablestransmission and/or reception of data through the 3GPP access, the WLANaccess, or both thereof. The first PDN connection may be themulti-access PDN connection.

Furthermore, the second PDN connection may be a known PDN connection,rather than the multi-access PDN connection. Note that the second PDNconnection may be a single-access PDN connection.

Here, the single-access PDN connection refers to one PDN connectionconstituted of only a transfer path through either the 3GPP access orthe WLAN access, unlike the multi-access PDN connection. In detail, thesingle-access PDN connection is a PDN connection established by theattach in the related art.

That is, the second PDN connection is a PDN connection including the EPSbearer through the access network A or a PDN connection including theGTP/PMIPv6 transfer path through the access network B. The second PDNconnection accommodates a transfer path and/or a communication paththrough either one of the access networks.

As described above, the single-access PDN connection is a PDN connectiondifferent from the multi-access PDN connection. Moreover, thesingle-access PDN connection denotes a PDN connection that is alsodifferent from a PDN connection for a Local IP Access (LIPA). Here, theLIPA denotes communication control for offloading the connection to ahome network. More specifically, the base station to which the terminaldevice connects performs the offload by transmitting, to the homenetwork to which the base station connects, user data that isconventionally delivered via the core network 90. The PDN connection forthe LIPA is a PDN connection for performing such communication based onthe LIPA.

Next, an example of a configuration of the core network 90 will bedescribed. FIG. 2A illustrates an example of a configuration of the IPmobile communication network. As illustrated in FIG. 2A, the corenetwork 90 includes a Home Subscriber Server (HSS) 50, anAuthentication, Authorization, Accounting (AAA) 55, a Policy andCharging Rules Function (PCRF) 60, the PGW 30, an enhanced Packet DataGateway (ePDG) 65, the SGW 35, the MME 40, and a Serving GPRS SupportNode (SGSN) 45.

Furthermore, the core network 90 is capable of connecting to multipleradio access networks (an LTE AN 80, a WLAN ANb 75, a WLAN ANa 70, aUTRAN 20, and a GERAN 25).

Such a radio access network may be constituted of multiple differentaccess networks, or may be constituted of either one of the accessnetworks. Moreover, the UE 10 is capable of connecting wirelessly to theradio access network.

Moreover, a WLAN Access Network b (WLAN ANb 75) that connects to thecore network 90 via the ePDG 65 and a WLAN Access Network a (WLAN ANa75) that connects to the PGW 30, the PCRF 60, and the AAA 55 can beconfigured as access networks to be connectable in a WLAN access system.

Note that the devices have a similar configuration to those of thedevices in the related art in a mobile communication system using EPS,and thus detailed descriptions will be omitted. The devices will bedescribed briefly, hereinafter.

The PGW 30 is connected to the PDN 100, the SGW 35, the ePDG 65, theWLAN ANa 70, the PCRF 60, and the AAA 55, and serves as a relay deviceconfigured to transfer user data by functioning as a gateway devicebetween the PDN 100 and the core network 90.

The SGW 35 is connected to the PGW 30, the MME 40, the LTE AN 80, theSGSN 45, and the UTRAN 20, and serves as a relay device configured totransfer user data by functioning as a gateway device between the corenetwork 90 and the 3GPP access network (the UTRAN 20, the GERAN 25, andthe LTE AN 80).

The MME 40 is connected to the SGW 35, the LTE AN 80, and the HSS 50,and serves as an access control device configured to perform locationinformation management and access control for the UE 10 via the LTE AN80. Furthermore, the core network 90 may include multiple locationmanagement devices. For example, a location management device differentfrom the MME 40 may be constituted. Like the MME 40, the locationmanagement device different from the MME 40 may be connected to the SGW35, the LTE AN 80, and the HSS 50.

Furthermore, when multiple MMEs 40 are included in the core network 90,the MMEs 40 may be connected to each other. With this configuration, thecontext of the UE 10 may be transmitted and/or received among the MMEs40.

The HSS 50 is connected to the MME 40 and the AAA 55, and serves as amanaging node configured to manage subscriber information. Thesubscriber information of the HSS 50 is referenced, for example, in theaccess control for the MME 40. Moreover, the HSS 50 may be connected tothe location management device different from the MME 40.

The AAA 55 is connected to the PGW 30, the HSS 50, the PCRF 60, and theWLAN ANa 70 and is configured to perform access control for the UE 10connected via the WLAN ANa 70.

The PCRF 60 is connected to the PGW 30, the WLAN ANa 75, the AAA 55, andthe PDN 100, and is configured to perform QoS management on datadelivery. For example, the PCRF 60 manages QoS of a communication pathbetween the UE 10 and the PDN 100.

The ePDG 65 is connected to the PGW 30 and the WLAN ANb 75, and isconfigured to deliver user data by functioning as a gateway devicebetween the core network 90 and the WLAN ANb 75.

The SGSN 45 is connected to the UTRAN 20, the GERAN 25, and the SGW 35,and serves as a control device for location management between a 3G/2Gaccess network (UTRAN/GERAN) and the LTE access network (E-UTRAN). Inaddition, the SGSN 45 has a function of selecting the PGW 30 and the SGW35, a function of managing a time zone of the UE 10; and a function ofselecting the MME 40 at the time of handover to the E-UTRAN.

Also, as illustrated in FIG. 2B, each radio access network includesdevices to which the UE 10 is actually connected (for example, a basestation device and an access point device), and the like. The devicesused in these connections are assumed to adapt to the radio accessnetworks.

In the present embodiment, an LTE AN 80 includes an eNB 45. The eNB 45is a radio base station to which the UE 10 connects in an LTE accesssystem, and the LTE AN 80 may include one or multiple radio basestations.

The WLAN ANa 70 includes a WLAN APa 72 and the TWAG 74. The WLAN APa 72is a radio base station to which the UE 10 connects in the WLAN accesssystem trusted by the operator running the core network 90, and the WLANANa 70 may include one or multiple radio base stations. The GW 74 is agateway device between the core network 90 and the WLAN ANa 70.Furthermore, the WLAN APa 72 and the GW 74 may be constituted as asingle device.

Even in a case where the operator running the core network 90 and theoperator running the WLAN ANa 70 are different from each other, such aconfiguration can be implemented through contracts and agreementsbetween the operators.

Furthermore, the WLAN ANb 75 includes a WLAN APb 76. The WLAN APb 76serves as a radio base station to which the UE 10 connects in the WLANaccess system, in a case where no trusting relationship is establishedwith the operator running the core network 90, and the WLAN ANb 75 mayinclude one or multiple radio base stations.

In this manner, the WLAN ANb 75 is connected to the core network 90 viathe ePDG 65, which is a device included in the core network 90, servingas a gateway. The ePDG 65 has a security function for ensuringcommunication security.

The UTRAN 20 includes a radio network controller (RNC) 24 and an eNB(UTRAN) 22. The eNB (UTRAN) 22 is a radio base station to which the UE10 connects through a UMTS Terrestrial Radio Access (UTRA), and theUTRAN 20 may include one or multiple radio base stations. Furthermore,the RNC 24 is a control unit configured to connect the core network 90and the eNB (UTRAN) 22, and the UTRAN 20 may include one or multipleRNCs. Moreover, the RNC 24 may be connected to one or multiple eNBs(UTRANs) 22. In addition, the RNC 24 may be connected to a radio basestation (Base Station Subsystem (BSS) 26) included in the GERAN 25.

The GERAN 25 includes the BSS 26. The BSS 26 is a radio base station towhich the UE 10 connects through GSM/EDGE radio access (GERA), and theGERAN 25 may be constituted of one or multiple radio base station BSSs.Furthermore, the multiple BSSs may be connected to each other. Moreover,the BSS 26 may be connected to the RNC 24.

Note that in the present specification, the UE 10 being connected toeach radio access network refers to the UE 10 being connected to a basestation device, an access point, or the like included in each radioaccess network, and data, signals, and the like being transmitted and/orreceived also traverse those base station devices, access points, or thelike.

2.2. Device Configuration

The configuration of each device will be described below.

2.2.1. TWAG Configuration

FIG. 3 illustrates a device configuration of the TWAG 74. As illustratedin FIG. 3, the TWAG 74 is constituted of an IP mobile communicationnetwork interface unit 320, a control unit 300, and a storage 340. TheIP mobile communication network interface unit 320 and the storage 340are connected to the control unit 300 via a bus.

The control unit 300 serves as a function unit for controlling the TWAG74. The control unit 300 implements various processes by reading out andexecuting various programs stored in the storage 340.

The IP mobile communication network interface unit 320 serves as a datatransmission and/or reception unit configured to transmit and/or receiveuser data and/or a control message, and serves as a function unitthrough which the TWAG 74 is connected to the PGW 30.

The storage 340 serves as a function unit for storing programs, data,and the like necessary for each operation of the TWAG 74. The storage340 includes, for example, a semiconductor memory, a Hard Disk Drive(HDD), or the like.

As illustrated in FIG. 3, the storage 340 stores a TWAG capability 342,a Network capability 344, and an EPS bearer context 346. Hereinafter,information elements stored in the storage 340 will be described.

FIGS. 4A to 4E illustrate the information elements stored in the storage340. FIG. 4A illustrates an example of the TWAG capability stored in theTWAG 74. In the TWAG capability, identification information (NBIFOMcapability) is stored for each TWAG 74, the information indicatingwhether the capability of establishing the first PDN connection issupported. In other words, the identification information indicateswhether the TWAG 74 supports an NBIFOM function. Specifically, theNBIFOM capability may include “allowed” or “Not allowed”.

Note that the NBIFOM function may be information indicating theprovision of the function of establishing the multi-access PDNconnection based on the NBIFOM.

Alternatively, the NBIFOM capability may be identification informationindicating the possession of the capability of establishing the firstPDN connection. That is, the existence of the NBIFOM capability in thestorage may mean that the TWAG 74 is a gateway capable of establishingthe first PDN connection. In other words, the existence of the NBIFOMcapability in the storage may mean that the TWAG 74 is a gatewaysupporting the NBIFOM function.

As illustrated in FIG. 4A, the NBIFOM capability may be stored inassociation with the TWAG ID that is the identification information onthe TWAG 74. In a case of not being associated with the TWAG ID, theNBIFOM capability may mean a capability of the TWAG 74 to be stored.

If the TWAG ID and the NBIFOM capability are stored in association witheach other, the TWAG 74 may store the TWAG capability of multiple TWAGs74.

In this case, when the UE 10 performs a handover to another TWAG 74, theTWAG 74 may select a TWAG 74 to which the handover is made, based on theTWAG Capability.

Next, the Network capability 344 will be described. FIG. 4B illustratesan example of the Network capability stored in the TWAG 74. In theNetwork capability, the NBIFOM capability is stored for each network,i.e., for each PGW 30.

Here, the NBIFOM capability denotes identification informationindicating whether the capability of establishing the first PDNconnection is supported for each network. In other words, theidentification information indicates whether the PGW 30 supports theNBIFOM function. More specifically, for example, the NBIFOM capabilitymay include “allowed” or “Not allowed”.

Note that the NBIFOM function may be information indicating theprovision of the function of establishing the multi-access PDNconnection based on the NBIFOM.

Alternatively, the NBIFOM capability may be identification informationindicating the possession of the capability of establishing the firstPDN connection. In other words, the NBIFOM capability may beidentification information indicating that a gateway supports the NBIFOMfunction. That is, the existence of the NBIFOM capability in the storagemay mean that the PGW 30 is a gateway having the function ofestablishing the first PDN connection. In other words, the existence ofthe NBIFOM capability in the storage may mean that the PGW 30 is agateway supporting the NBIFOM function.

As illustrated in FIG. 4B, the TWAG 74 stores an NBIFOM capability inassociation with a PGW ID. Furthermore, as illustrated in FIG. 4B, theNBIFOM capability may be stored in association with each of multiplePGWs 30.

The PGW ID may be any information for identifying the PGW 30, and may bean access point name (APN), for example.

Next, the EPS bearer context will be described. The EPS bearer contextmay be classified into the EPS bearer context for each UE 10 stored foreach UE 10, the EPS bearer context for each PDN connection, and the EPSbearer context for each bearer and/or transfer path.

FIG. 4C illustrates information elements included in the EPS bearercontext for each UE 10. As is obvious from FIG. 4C, the TWAG 74 stores,for each UE 10, a UE NBIFOM capability and an NBIFOM allowed.

The UE NBIFOM capability is the NBIFOM capability of the UE 10. The UENBIFOM capability is identification information for each UE 10indicating whether capability of establishing the first PDN connectionis supported. In other words, the UE NBIFOM capability is identificationinformation indicating whether the UE 10 supports the NBIFOM function.More specifically, for example, the UE NBIFOM capability may include“allowed” or “Not allowed”.

Note that the NBIFOM function may be information indicating theprovision of the function of establishing the multi-access PDNconnection based on the NBIFOM.

Alternatively, the UE NBIFOM capability may be identificationinformation indicating that the UE 10 has the capability of establishingthe first PDN connection. That is, the existence of the UE NBIFOMcapability may mean that the UE 10 has a function of establishing thefirst PDN connection.

In other words, the UE NBIFOM capability may be identificationinformation indicating that the UE 10 supports the NBIFOM function. Thatis, the existence of the UE NBIFOM capability in the storage may meanthat the UE 10 supports the NBIFOM function.

Furthermore, the NBIFOM allowed is identification information indicatingan APN that is allowed to establish a PDN connection using the NBIFOM.The NBIFOM may be associated with at least the APN. The NBIFOM allowedmay be associated with multiple APNs.

In the present embodiment, the APN 1 is associated with the NBIFOMallowed. That is, the APN 1 is allowed to establish the multi-access PDNconnection based on the NBIFOM based on the NBIFOM. In other words, inthe present embodiment, the UE 10 is allowed to establish themulti-access PDN connection based on the NBIFOM by using the APN 1. Notethat the APN 1 is also allowed to establish the PDN connection of therelated art, rather than the multi-access PDN connection based on theNBIFOM.

In addition, in the present embodiment, the APN 2 is not associated withthe NBIFOM allowed. That is, in the present embodiment, the APN 2 is notallowed to establish the multi-access PDN connection based on theNBIFOM. That is, in the present embodiment, the UE 10 cannot establishthe multi-access PDN connection based on the NBIFOM by using the APN 2.

The NBIFOM allowed may be stored before the PDN connection isestablished.

The TWAG 74 may access the HSS 50 to acquire the NBIFOM allowed, beforethe PDN connection is established and/or while the establishmentprocedure is being performed.

Furthermore, the EPS bearer context for each UE 10 may includeidentification information on the UE 10. The identification informationof the UE 10 may be an IMSI.

Furthermore, FIG. 4D illustrates the EPS bearer context for each PDNconnection. The EPS bearer context for each PDN connection includes aPDN connection ID, a Network allowed mode, an Operation mode, a Userplane connection ID, a TWAG MAC address, and an NBIFOM Permission.

The PDN connection ID is identification information for identifying aPDN connection. The UE 10, the TWAG 74, and the PGW 30 may store thesame identification information.

The Operation mode is identification information of a mode thatindicates which one of the UE 10 and a network takes an initiative intransmitting and/or receiving data or is allowed to initiatecommunication control in a case where the PDN connection is the firstPDN connection.

More specifically, for example, an Operation mode that allows the UE 10to initiate the communication control may be the UE initiated mode.

Furthermore, an Operation mode that allows the network and/or the PGW 30and/or the PCRF 60 to initiate the communication control may be aNetwork initiated mode.

The Network allowed mode indicates an Operation mode allowed by thenetwork. The Network allowed mode may include the UE initiated mode, theNetwork initiated mode, or both thereof.

The User plane connection ID is identification information foridentifying a connection used for transmission of user data when the UE10 establishes a transfer path via the TWAG 74.

The TWAG MAC address is a physical address of the TWAG 74.

The NBIFOM permission is information indicating that this PDN connectionhas established the multi-access PDN connection based on the NBIFOM. Inother words, the NBIFOM permission indicates that the first PDNconnection has been established.

That is, the TWAG 74 having stored the NBIFOM permission means that thisPDN connection is the first PDN connection.

The NBIFOM permission is identification information that is stored inthe TWAG 74 upon the PDN connection being established.

The TWAG 74 may access the HSS 50 to acquire the NBIFOM permissionduring the establishment of the PDN connection. Alternatively, the TWAG74 may store the NBIFOM Permission on the basis of the establishment ofthe multi-access PDN connection based on the NBIFOM.

Next, the EPS bearer context for each bearer and/or transfer path willbe described. As illustrated in FIG. 4E, the EPS bearer context for eachbearer and/or transfer path may include the transfer path identificationinformation and a Routing Rule.

The transfer path identification information is information foridentifying a transfer path and/or bearer. The transfer pathidentification information may be an EPS bearer ID, for example.

The Routing Rule indicates an association of a Routing Filter, and aRouting address or Routing access type. Whether using a communicationpath through the 3GPP access network or using a communication paththrough the WLAN access network is determined, based on such anassociation.

Here, the Routing access type indicates an access network through whichthe flow passes. For example, the Routing access type indicates the 3GPPor the WLAN.

Furthermore, the Routing address indicates an IP address through whichthe flow can pass. For example, the Routing address may be an IP addressof the SGW 35. Alternatively, the Routing address may be an IP addressof the TWAG 74. Alternatively, the Routing address may be an IP addressof a Mobile Access Gateway (MAG).

The Routing Rule may be notified from the PGW 30 or the PCRF 60, or maybe notified from the UE 10. Alternatively, the Routing Rule may be avalue that the TWAG 74 prestores as a default value.

An IP flow may be switched by including an IP header in the RoutingFilter. Alternatively, the flow may be switched for each application byincluding an application ID in the Routing Filter. Alternatively, theRouting Filter may include the TFT.

The Routingu Rule may store multiple rules. Furthermore, the Routingrule may include priority for each rule.

The TWAG Capability and the Network capability may be included in theEPS bearer context.

2.2.2. HSS Configuration

Next, the configuration of the HSS 50 will be described. FIG. 5illustrates a device configuration of the HSS 50. As illustrated in FIG.5, the HSS 50 is constituted of an IP mobile communication networkinterface unit 520, a control unit 500, and a storage 540. The IP mobilecommunication network interface unit 520 and the storage 540 areconnected to the control unit 500 via a bus.

The control unit 500 serves as a function unit for controlling the HSS50. The control unit 500 implements various processes by reading out andexecuting various programs stored in the storage 540.

The IP mobile communication network interface unit 520 serves as a datatransmission and/or reception unit configured to transmit and/or receiveuser data and/or a control message, and also serves as a function unitfor connecting the HSS 50 to the MME 40 and/or another MME 40, and theAAA 55.

The storage 540 serves as a function unit for storing programs, data,and the like necessary for each operation of the HSS 50. The storage 540includes, for example, a semiconductor memory, a Hard Disk Drive (HDD),or the like.

As illustrated in FIG. 5, the storage 540 stores HSS data 542.Hereinafter, information elements stored in the storage 540 will bedescribed.

FIGS. 6A and 6B illustrate the information elements stored in thestorage 540. FIG. 6A illustrates an example of HSS data for each UE 10to be stored in the HSS 50.

As is obvious from FIG. 6A, the HSS data for each UE 10 includes anIMSI, an MSISDN, an IMEI/IMEISV, an Access Restriction, a UE NBIFOMcapability, and an NBIFOM allowed.

The IMSI is identification information to be assigned to a user(subscriber) using the UE 10.

The MSISDN represents the phone number of the UE 10.

The IMEI/IMISV is identification information assigned to the UE 10.

The Access Restriction indicates registration information for accessrestriction.

The UE NBIFOM capability is the NBIFOM capability of the UE 10. The UENBIFOM capability is identification information for each UE 10indicating whether capability of establishing the first PDN connectionis supported. In other words, the UE NBIFOM capability indicates whetherthe UE 10 supports the NBIFOM function. More specifically, for example,the NBIFOM capability may include “allowed” or “Not allowed”.

Alternatively, the UE NBIFOM capability may be identificationinformation indicating that the UE 10 has the capability of establishingthe first PDN connection. That is, the existence of the UE NBIFOMcapability may mean that the UE 10 has a function of establishing thefirst PDN connection.

Furthermore, the NBIFOM allowed is identification information indicatingan APN that is allowed to establish a PDN connection using the NBIFOM.The NBIFOM may be associated with at least the APN. The NBIFOM allowedmay be associated with multiple APNs.

In the present embodiment, the APN 1 is associated with the NBIFOMallowed. That is, the APN 1 is allowed to establish the multi-access PDNconnection based on the NBIFOM. In other words, in the presentembodiment, the UE 10 is allowed to establish the multi-access PDNconnection based on the NBIFOM by using the APN 1. Note that the APN 1is also allowed to establish the PDN connection of the related art,rather than the multi-access PDN connection based on the NBIFOM.

In addition, in the present embodiment, the APN 2 is not associated withthe NBIFOM allowed. That is, in the present embodiment, the APN 2 is notallowed to establish the multi-access PDN connection based on theNBIFOM. That is, in the present embodiment, the UE 10 cannot establishthe multi-access PDN connection based on the NBIFOM by using the APN 2.

The NBIFOM allowed may be stored before the PDN connection isestablished.

FIG. 6B illustrates an example of HSS data for each PDN connectionstored in the HSS 50. As seen from FIG. 6B, the HSS data for each PDNconnection includes at least a Context ID, a PDN address, a PDN Type, anAccess Point Name (APN), a WLAN offlaod ability, a PDN GW ID, and anNBIFOM Permission.

The Context ID is identification information of the context storing theHSS data for each PDN connection.

The PDN Address represents a registered IP address. The PDN Address isan IP address of the UE 10.

The PDN Type indicates the type of PDN Address. That is, the PDN Type isidentification information for identifying IPv4, IPv6, or IPv4v6, forexample.

The APN is a label indicating an access destination in the network, inaccordance with the DNS naming convention.

The WLAN offload ability is identification information indicatingwhether traffic connected through the APN can be offloaded to the WLANby utilizing a cooperative function between the WLAN and the 3GPP, orthe 3GPP connection is maintained. The WLAN offload ability may vary foreach RAT type. Specifically, the LTE (E-UTRA) and the 3G (UTRA) may havedifferent WLAN offload ability.

The PDN GW identity is identification information for identifying thePGW 30 utilized in this APN. This identification information may be aFully Qualified Domain Name (FQDN) or an IP address.

The NBIFOM permission is information indicating that the PDN connectionhas established the multi-access PDN connection based on the NBIFOM. Inother words, the NBIFOM permission indicates that the first PDNconnection has been established.

That is, the TWAG 74 having stored the NBIFOM permission means that thisPDN connection is the first PDN connection.

The NBIFOM permission is identification information that is stored inthe TWAG 74 upon the PDN connection being established.

Specifically, for example, the HSS data for each PDN connectionincluding the APN 1 may include the NBIFOM permission, and the HSS datafor each PDN connection including the APN 2 need not include the NBIFOMPermission.

In other words, the PDN connection based on the APN 1 may be the firstPDN connection, and the PDN connection based on the APN 2 cannot be thefirst PDN connection.

2.2.3. UE Configuration

Next, the configuration of the UE 10 will be described. FIG. 7illustrates a device configuration of the UE 10. As illustrated in FIG.7, the UE 10 is constituted of an LTE interface unit 720, a WLANinterface unit 740, a control unit 700, and a storage 750.

The LTE interface unit 720, the WLAN interface unit 740, and the storage750 are connected to the control unit 700 via a bus.

The control unit 700 serves as a function unit for controlling the UE10. The control unit 700 implements various processes by reading out andexecuting various programs stored in the storage 750.

The LTE interface unit 720 serves as a data transmission and/orreception unit configured to transmit and/or receive user data and/or acontrol message, and also serves as a function unit through which the UE10 connects to an IP access network via an LTE base station.Furthermore, an external antenna 710 is connected to the LTE interfaceunit 720.

The WLAN interface unit 740 serves as a data transmission and/orreception unit configured to transmit and/or receive user data and/or acontrol message, and also serves as a function unit through which the UE10 connects to a WLAN AP and connects to the IP access network.Furthermore, an external antenna 730 is connected to the WLAN interfaceunit 740.

The control unit 700 serves as a function unit for controlling the UE10. The control unit 700 implements various processes by reading out andexecuting various programs stored in the storage 750.

The storage 750 is a function unit for storing programs, data, and thelike necessary for each operation of the UE 10. The storage 750 isconfigured with, for example, a semiconductor memory, a Hard Disk Drive(HDD), or the like.

As illustrated in FIG. 7, the storage 750 stores a UE context 752.Hereinafter, information elements stored in the storage 750 will bedescribed. Note that the UE context 752 is classified into a UE contextfor each UE 10, a UE context for each PDN connection, and a UE contextfor each transfer path and/or bearer.

FIG. 8A is an example of the UE context stored for each UE 10. Asillustrated in FIG. 8A, the UE context for each UE 10 includes an IMSI,an EMM State, a GUTI, an ME Identity, and a UE NBIFOM capability.

The IMSI is identification information to be assigned to a user(subscriber) using the UE 10.

The EMM State indicates a mobility management state of the UE 10. Forexample, the EMM State may be EMM-REGISTERED in which the UE 10 isregistered with the network (registered state) or EMM-REREGISTERED inwhich the UE 10 is not registered with the network (reregistered state).

The GUTI is an abbreviation of “Globally Unique Temporary Identity,” andis temporary identification information of the UE 10. The GUTI isconfigured with identification information of the MME 40 (GloballyUnique MME Identifier (GUMMEI)) and identification information of the UE10 in a specific MME 40 (M-TMSI).

The ME identity is an ID of an ME, and may be the IMEI/IMISV, forexample.

The UE NBIFOM capability is the NBIFOM capability of the UE 10. The UENBIFOM capability is identification information for each UE 10indicating whether capability of establishing the first PDN connectionis supported. In other words, the UE NBIFOM capability is identificationinformation for each UE 10 indicating whether the NBIFOM function issupported. More specifically, for example, the NBIFOM capability mayinclude “allowed” or “Not allowed”.

Note that the NBIFOM function may be information indicating theprovision of the function of establishing the multi-access PDNconnection based on the NBIFOM.

Alternatively, the UE NBIFOM capability may be identificationinformation indicating that the UE 10 has the capability of establishingthe first PDN connection. That is, the existence of the UE NBIFOMcapability in the storage of the UE 10 may mean that the UE 10 has thefunction of establishing the first PDN connection.

In other words, the UE NBIFOM capability may be identificationinformation indicating that the UE 10 supports the NBIFOM function. Thatis, the existence of the UE NBIFOM capability in the storage of the UE10 may mean that the UE 10 supports the NBIFOM function.

FIG. 8B illustrates an example of the UE context for each PDNconnection. As illustrated in FIG. 8B, the UE context for each PDNconnection includes at least a PDN connection ID, an APN in Use, an IPaddress, a Default Bearer, a WLAN offload ability, a UE allowed mode,and an Operation mode.

The PDN connection ID is identification information for identifying aPDN connection. The UE 10, the TWAG 74, and the PGW 30 may store thesame identification information.

The APN in Use is an APN utilized by the UE 10 most recently. This APNmay include identification information of the network and identificationinformation of a default operator.

The IP Address is an IP address assigned to the UE 10 through the PDNconnection, and may be an IPv4 address or an IPv6 prefix.

The Default Bearer is EPS bearer identification information foridentifying a default bearer in this PDN connection.

Note that the UE 10 may establish multiple default bearers for a PDNconnection, in a case where the PDN connection is a multi-access PDNconnection. Therefore, the multi-access PDN connection may be managed inassociation with the multiple default bearers. Specifically, EPS beareridentification information corresponding to each default bearer may bemanaged in association with the multi-access PDN connection.

Furthermore, the UE 10 may manage a default bearer and an access networkin association with each other.

Specifically, the UE 10 may store the EPS bearer identificationinformation identifying each of the default bearer for the accessnetwork A and the default bearer for access network B. Here, the defaultbearer for an access network may be a default bearer for an accesssystem of the access network. Therefore, the UE 10 may store a defaultbearer for a 3GPP access and a default bearer for a WLAN access inassociation with a multi-access PDN connection.

The default bearer for the multi-access PDN may be a default bearerestablished by the UE 10. In other words, the UE 10 stores one defaultbearer for the multi-access PDN connection in a state where only onedefault bearer is established for the multi-access PDN connection, andthe UE 10 may store two default bearers for the multi-access PDNconnection in a state where two default bearers are established for themulti-access PDN connection.

Furthermore, the UE 10 may store, with respect to the multi-access PDNconnection, information indicating default access (Default Assess) inthe multi-access PDN connection. Note that the default access may beinformation indicating the 3GPP access or the WLAN access. The 3GPPaccess may be an access system that is not the WLAN access. Morespecifically, the 3GPP access may be information indicating an accessnetwork including an E-UTRAN access, a UTRAN access, and a GERAN access.

Alternatively, the default access may include more detailed information.For example, the default access may be one of E-UTRAN access, UTRANaccess, and GERAN access.

In a case where multiple default bearers are established, the UE 10 mayselect a default bearer based on the default access, and may transmitand/or receive user data by using the selected default bearer.

The WLAN offload ability is WLAN offload permission informationindicating whether a communication associated with the PDN connectionallows offloading the connection to the WLAN by using an interworkingfunction between the WLAN and the 3GPP, or the 3GPP access ismaintained.

The UE allowed mode is an operation mode allowed by the UE 10. Thisidentification information may indicate the UE intiated mode, theNetwork initiated mode, or both thereof.

The Operation mode is identification information of a mode thatindicates which one of the UE 10 and a network takes an initiative intransmitting and/or receiving data or is allowed to initiatecommunication control in a case where the current PDN connection is thefirst PDN connection.

FIG. 8C illustrates the UE context for each bearer. The UE context foreach bearer includes transfer path identification information and aRouting Rule.

The transfer path identification information is information foridentifying a transfer path and/or bearer. The transfer pathidentification information may be an EPS bearer ID, for example.

Furthermore, the transfer path identification information may beassociated with the TFT.

Here, the Routing access type indicates an access network through whichthe flow passes. For example, the Routing access type indicates the 3GPPor the WLAN.

Furthermore, the Routing address indicates an IP address through whichthe flow can pass. For example, the Routing address may be an IP addressof the SGW 35. Alternatively, the Routing address may be an IP addressof the TWAG 74. Alternatively, the Routing address may be an IP addressof a Mobile Access Gateway (MAG).

The Routing Rule may be notified from the PGW 30 or the PCRF 60.Alternatively, the Routing Rule may be a value that the UE 10 prestoresas a default value.

An IP flow may be switched by including an IP header in the RoutingFilter. Alternatively, the UE 10 may switch the flow for eachapplication by including an application ID in the Routing Filter.Alternatively, the Routing Filter may include a TFT.

The Routingu Rule may store multiple rules (regulations). Furthermore,the Routing rule may include priority for each rule.

FIG. 8D illustrates the TWAG Capability. In the TWAG capability,identification information (NBIFOM capability) is stored for each TWAG74, the information indicating whether the capability of establishingthe first PDN connection is supported. In other words, theidentification information indicates whether the TWAG 74 supports anNBIFOM function. Specifically, the NBIFOM capability may include“allowed” or “Not allowed”.

Note that the NBIFOM function may be information indicating theprovision of the function of establishing the multi-access PDNconnection based on the NBIFOM.

Alternatively, the NBIFOM capability may be identification informationindicating the possession of the capability of establishing the firstPDN connection. That is, the existence of the NBIFOM capability in thestorage may mean that the TWAG 74 is a gateway capable of establishingthe first PDN connection. In other words, the existence of the NBIFOMcapability in the storage may mean that the TWAG 74 is a gatewaysupporting the NBIFOM function.

The UE 10 may store the NBIFOM capability associated with the TWAG ID.Furthermore, the NBIFOM capability of multiple TWAGs 74 may be stored.

FIG. 8E illustrates an example of the Network capability. In the Networkcapability, the NBIFOM capability is stored for each network, i.e., foreach PGW 30.

Here, the NBIFOM capability denotes identification informationindicating whether the capability of establishing the first PDNconnection is supported for each network. More specifically, forexample, the NBIFOM capability may include “allowed” or “Not allowed”.

Alternatively, the NBIFOM capability may be identification informationindicating the possession of the capability of establishing the firstPDN connection. That is, the existence of the NBIFOM capability may meanthat the PGW 30 and/or the network is a gateway having the function ofestablishing the first PDN connection.

As illustrated in FIG. 8E, the TWAG 74 stores the NBIFOM capability inassociation with the PGW ID. Furthermore, as illustrated in FIG. 8E, theNBIFOM capability may be stored in association with each of multiplePGWs 30.

The PGW ID is information for identifying the PGW 30. The PGW ID may bean APN, for example.

The TWAG Capability and the Network capability may be included in the UEcontext, or may be information separated from the UE context.

That is, the UE 10 may store the TWAG Capability and the Networkcapability included in the UE context, or may store the TWAG Capabilityand the Network capability separately from the UE context.

2.2.4. PGW Components

Next, the components of the PGW 30 will be described. FIG. 9 illustratesa device configuration of the PGW 30. As illustrated in FIG. 9, the PGW30 is constituted of an IP mobile communication network interface unit920, a control unit 900, and a storage 940. The IP mobile communicationnetwork interface unit 920 and the storage 940 are connected to thecontrol unit 900 via a bus.

The control unit 900 serves as a function unit for controlling the PGW30. The control unit 900 implements various processes by reading out andexecuting various programs stored in the storage 940.

The IP mobile communication network interface unit 920 serves as a datatransmission and/or reception unit configured to transmit and/or receiveuser data and/or a control message, and also serves as a function unitthrough which the PGW 30 is connected to the SGW 35 and/or the PCRF 60and/or the ePDG 65 and/or the AAA 55 and/or the GW 74.

The storage 940 serves as a function unit for storing programs, data,and the like necessary for each operation of the PGW 30. The storage 940is configured with, for example, a semiconductor memory, a Hard DiskDrive (HDD), or the like.

As illustrated in FIG. 9, the storage 940 stores an EPS bearer context942. Note that an EPS bearer context includes an EPS bearer contextstored for each UE 10, an EPS bearer context stored for each APN, an EPSbearer context stored for each PDN connection, and an EPS bearer contextstored for each transfer path and/or bearer.

First, the EPS bearer context for each UE 10 will be described. FIG. 10Aillustrates an example of the EPS bearer context for each UE 10. Asillustrated in FIG. 10A, the EPS bearer context includes at least anIMSI, an ME identity, an MSISDN, and a UE NBIFOM capability.

The IMSI is information for identifying a user of the UE 10.

The ME identity is an ID of an ME, and may be the IMEI/IMISV, forexample.

The MSISDN represents the phone number of the UE 10.

The UE NBIFOM capability is the NBIFOM capability of the UE 10.

The UE NBIFOM capability is identification information for each UE 10indicating whether capability of establishing the first PDN connectionis supported. More specifically, for example, the NBIFOM capability mayinclude “allowed” or “Not allowed”.

Alternatively, the UE NBIFOM capability may be identificationinformation indicating that the UE 10 has the capability of establishingthe first PDN connection. That is, the existence of the UE NBIFOMcapability may mean that the UE 10 has a function of establishing thefirst PDN connection.

Next, the EPS bearer context for each PDN connection will be described.FIG. 10B illustrates an example of the EPS bearer context for each PDNconnection.

As illustrated in FIG. 10B, the context includes at least a PDNconnection ID, an IP address, a PDN type, an APN, a Network allowedmode, and an Operation mode.

The PDN connection ID is identification information for identifying aPDN connection. The UE 10, the TWAG 74, and the PGW 30 may store thesame identification information.

The IP Address indicates an IP address assigned to the UE 10 for the PDNconnection. The IP address may be an IPv4 and/or IPv6 prefix.

The PDN type indicates the type of the IP address. The PDN typeindicates IPv4, IPv6, or IPv4v6, for example.

The APN is a label indicating an access destination in the network, inaccordance with the DNS naming convention.

The Network allowed mode indicates an Operation mode allowed by thenetwork. The Network allowed mode may include the UE initiated mode, theNetwork initiated mode, or both thereof.

The Operation mode is identification information of a mode thatindicates which one of the UE 10 and a network takes an initiative intransmitting and/or receiving data or is allowed to initiatecommunication control in a case where the current PDN connection is thefirst PDN connection.

More specifically, for example, the UE initiated mode in which the UE 10is allowed to initiate the communication control or the Networkinitiated mode in which the network is allowed to initiate thecommunication control may be identified.

Next, an example of the EPS bearer context for each transfer path and/orbearer will be described with reference to FIG. 10C. As illustrated inFIG. 10C, the context includes at least transfer path identificationinformation and a Routing Rule.

The transfer path identification information is information foridentifying a transfer path and/or bearer. The transfer pathidentification information may be an EPS bearer ID, for example.

Furthermore, the transfer path identification information may beassociated with the TFT.

The Routing access type indicates an access network through which theflow passes. For example, the Routing access type indicates the 3GPP orthe WLAN.

Furthermore, the Routing address indicates an IP address through whichthe flow can pass. For example, the Routing address may be an IP addressof the SGW 35. Alternatively, the Routing address may be an IP addressof the TWAG 74. Alternatively, the Routing address may be an IP addressof a Mobile Access Gateway (MAG).

The Routing Rule may be notified from the PGW 30 or the PCRF 60.Alternatively, the Routing Rule may be a value that the UE 10 prestoresas a default value.

The PGW 30 may switch the IP flow by including an IP header in theRouting Filter. Alternatively, the PGW 30 may switch the flow for eachapplication by including an application ID in the Routing Filter.Alternatively, the Routing Filter may include a TFT.

The Routingu Rule may store multiple rules. Furthermore, the Routingrule may include priority for each rule.

Furthermore, the PGW 30 may establish the default bearer for each PDNconnection established with the UE 10, and store the EPS beareridentification information identifying the default bearer.

Note that the PGW 30 may establish multiple default bearers for a PDNconnection, in a case where the PDN connection is a multi-access PDNconnection. Therefore, the multi-access PDN connection may be managed inassociation with the multiple default bearers. Specifically, EPS beareridentification information corresponding to each default bearer may bemanaged in association with the multi-access PDN connection.

Furthermore, the PGW 30 may manage the default bearers and the accessnetwork in association with each other.

Specifically, the PGW 30 may store the EPS bearer identificationinformation identifying each of the default bearer for the accessnetwork A and the default bearer for access network B. Here, the defaultbearer for an access network may be a default bearer for an accesssystem of the access network. Therefore, the PGW 30 may store thedefault bearer for 3GPP access and the default bearer for a WLAN accessin association with the multi-access PDN connection.

The default bearer for the multi-access PDN may be a default bearer thatis being established between the PGW 30 and the UE 10. In other words,the PGW 30 stores one default bearer for the multi-access PDN connectionin a state where only one default bearer is established for themulti-access PDN connection, and the PGW 30 may store two defaultbearers for the multi-access PDN connection in a state where two defaultbearers are established for the multi-access PDN connection.

Furthermore, the PGE 30 may store information indicating a defaultaccess (Default Assess) in the multi-access PDN connection, for themulti-access PDN connection. Note that the default access may beinformation indicating the 3GPP access or the WLAN access. The 3GPPaccess may be an access system that is not the WLAN access. Morespecifically, the 3GPP access may be information indicating an accessnetwork including the E-UTRAN access, the UTRAN access, and the GERANaccess.

Alternatively, the default access may include more detailed information.For example, the default access may be one of E-UTRAN access, UTRANaccess, and GERAN access.

When multiple default bearers are established, the PGW 30 may select adefault bearer based on the default access, and transmit and/or receiveuser data by using the selected default bearer.

FIG. 10D illustrates the TWAG Capability. In the TWAG capability,identification information (NBIFOM capability) is stored for each TWAG74, the information indicating whether the capability of establishingthe first PDN connection is supported. In other words, theidentification information indicates whether the TWAG 74 supports anNBIFOM function. Specifically, the NBIFOM capability may include“allowed” or “Not allowed”.

Note that the NBIFOM function may be information indicating theprovision of the function of establishing the multi-access PDNconnection based on the NBIFOM.

Alternatively, the NBIFOM capability may be identification informationindicating the possession of the capability of establishing the firstPDN connection. That is, the existence of the NBIFOM capability in thestorage may mean that the TWAG 74 is a gateway capable of establishingthe first PDN connection. In other words, the existence of the NBIFOMcapability in the storage may mean that the TWAG 74 is a gatewaysupporting the NBIFOM function.

The PGW 30 may store the NBIFOM capability associated with the TWAG ID.

FIG. 10E illustrates an example of the Network capability. In theNetwork capability, the NBIFOM capability is stored for each network,i.e., for each PGW 30.

Here, the NBIFOM capability denotes identification informationindicating whether the capability of establishing the first PDNconnection is supported for each network. More specifically, forexample, the NBIFOM capability may include “allowed” or “Not allowed”.

Alternatively, the NBIFOM capability may be identification informationindicating the possession of the capability of establishing the firstPDN connection. That is, the existence of the NBIFOM capability may meanthat the PGW 30 and/or the network is a gateway having the function ofestablishing the first PDN connection.

As illustrated in FIG. 10E, the PGW 30 stores the NBIFOM capability inassociation with the PGW ID. Furthermore, as illustrated in FIG. 10E,the NBIFOM capability may be stored in association with each of themultiple PGWs 30.

The PGW ID may be any information for identifying the PGW 30, and may bean APN, for example.

The TWAG Capability and the Network capability may be included in theEPS bearer context, or may be information separated from the UE context.

2.2.5. PCRF Components

Next, components of the PCRF 60 will be described. FIG. 11 illustrates adevice configuration of the PCRF 60. As illustrated in FIG. 11, the PCRF60 is constituted of an IP mobile communication network interface unit1120, a control unit 1100, and a storage 1140. The IP mobilecommunication network interface unit 1120 and the storage 1140 areconnected to the control unit 1100 via a bus.

The control unit 1100 serves as a function unit for controlling the PCRF60. The control unit 1100 implements various processes by reading outand executing various programs stored in the storage 1140.

The IP mobile communication network interface unit 1120 serves as a datatransmission and/or reception unit configured to transmit and/or receiveuser data and/or a control message, and also serves as a function unitthrough which the PCRF 60 is connected to the PGW 30 and/or the TWAG 74and/or the AAA 55.

The storage 1140 serves as a function unit for storing programs, data,and the like necessary for each operation of the PCRF 60. The storage940 is configured with, for example, a semiconductor memory, a Hard DiskDrive (HDD), or the like.

As illustrated in FIG. 11, the storage 1140 stores UE context 1142. Notethat the UE context may be classified into a UE context stored for eachUE 10 and a UE context stored for each PDN connection.

FIG. 12A illustrates the UE context for each UE 10. As illustrated inFIG. 12A, the context includes at least a Subscriber ID and UE NBIFOMcapability.

The Subscriber ID is identification information of a user. For example,the subscriber ID may be an IMSI.

The UE NBIFOM capability is the NBIFOM capability of the UE 10. The UENBIFOM capability is identification information for each UE 10indicating whether capability of establishing the first PDN connectionis supported. In other words, the UE NBIFOM capability is identificationinformation indicating whether the UE 10 supports the NBIFOM function.More specifically, for example, the NBIFOM capability may include“allowed” or “Not allowed”.

Alternatively, the UE NBIFOM capability may be identificationinformation indicating that the UE 10 has the capability of establishingthe first PDN connection. That is, the existence of the UE NBIFOMcapability may mean that the UE 10 has a function of establishing thefirst PDN connection.

In other words, the UE NBIFOM capability may be identificationinformation indicating that the UE 10 supports the NBIFOM function. Thatis, the existence of the UE NBIFOM capability in the storage may meanthat the UE 10 supports the NBIFOM function.

Next, the UE context for each PDN connection will be described. FIG. 12Billustrates an example of the UE context for each PDN connection. Asillustrated in FIG. 12B, the context may include at least an APN, anOperation mode, a Network Policy, a Charging Rule, a PCC Rule, and a QoSRule.

The APN is a label indicating an access destination in the network, inaccordance with the DNS naming convention.

The Operation mode is identification information of a mode thatindicates which one of the UE 10 and a network takes an initiative intransmitting and/or receiving data or is allowed to initiatecommunication control in a case where the PDN connection is the firstPDN connection.

More specifically, for example, an Operation mode that allows the UE 10to initiate the communication control may be the UE initiated mode.

Furthermore, an Operation mode that allows the network and/or the PGW 30and/or the PCRF 60 to initiate the communication control may be aNetwork initiated mode.

The Network Policy is a communication control policy on the networkside, and may include the Network allowed mode. Alternatively, the PCRF60 may store the Network allowed mode separately from the NetworkPolicy.

The Charging Rule is a regulation on charging. In accordance with theCharging Rule determined by the PCRF 60, a PCEF performs charging.

The PCC Rule is a regulation relating to control of the Network Policyand Charging Rule. In accordance with the PCC Rule, the PCEF performscommunication control and charging.

The QoS Rule is a regulation relating to QoS of the flow. The QoS Rulemay be associated with the PCC Rule.

FIG. 12C illustrates the UE context for each transfer path and/orbearer. As illustrated in FIG. 12C, the UE context for each transferpath and/or bearer includes at least a Routing Rule.

The Routing Rule indicates an association of a Routing Filter, and aRouting address or Routing access type. According to such anassociation, whether using a communication path through the 3GPP accessnetwork or using a transfer path through the WLAN access network isdetermined.

Here, the Routing access type indicates an access network through whichthe flow passes. For example, the Routing access type indicates the 3GPPor the WLAN.

Furthermore, the Routing address indicates an IP address through whichthe flow can pass. For example, the Routing address may be an IP addressof the SGW 35. Alternatively, the Routing address may be an IP addressof the TWAG 74. Alternatively, the Routing address may be an IP addressof a Mobile Access Gateway (MAG).

The Routing Rule may be notified from the UE 10 and/or the TWAG 74and/or the PGW 30. Alternatively, the Routing Rule may be a value thatthe PCRF 60 prestores as a default value. In this case, the PCRF 60 maydetermine the default value of the Routing Rule in accordance with thePCC Rule.

An IP flow may be switched by including an IP header in the RoutingFilter. Alternatively, the flow may be switched for each application byincluding an application ID in the Routing Filter. Alternatively, theRouting Filter may include the TFT.

The Routingu Rule may store multiple rules. Furthermore, the Routingrule may include priority for each rule.

FIG. 12D illustrates an example of the TWAG capability stored in theTWAG 74. In the TWAG capability, identification information (NBIFOMcapability) is stored for each TWAG 74, the information indicatingwhether the capability of establishing the first PDN connection issupported. In other words, the identification information indicateswhether the TWAG 74 supports an NBIFOM function. Specifically, theNBIFOM capability may include “allowed” or “Not allowed”.

Note that the NBIFOM function may be information indicating theprovision of the function of establishing the multi-access PDNconnection based on the NBIFOM.

Alternatively, the NBIFOM capability may be identification informationindicating the possession of the capability of establishing the firstPDN connection. That is, the existence of the NBIFOM capability in thestorage may mean that the TWAG 74 is a gateway capable of establishingthe first PDN connection. In other words, the existence of the NBIFOMcapability in the storage may mean that the TWAG 74 is a gatewaysupporting the NBIFOM function.

As illustrated in FIG. 12D, the NBIFOM capability may be stored inassociation with the TWAG ID that is the identification information onthe TWAG 74. In a case of not being associated with the TWAG ID, theNBIFOM capability may mean a capability of the TWAG 74 to be stored.

If the TWAG ID and the NBIFOM capability are stored in association witheach other, the PCRF 60 may store the TWAG capability of multiple TWAGs74.

FIG. 12E illustrates an example of the Network capability stored in thePCRF 60. In the Network capability, the NBIFOM capability is stored foreach network, i.e., for each PGW 30.

Here, the NBIFOM capability denotes identification informationindicating whether the capability of establishing the first PDNconnection is supported for each network. In other words, theidentification information indicates whether the PGW 30 supports theNBIFOM function. More specifically, for example, the NBIFOM capabilitymay include “allowed” or “Not allowed”.

Note that the NBIFOM function may be information indicating theprovision of the function of establishing the multi-access PDNconnection based on the NBIFOM.

Alternatively, the NBIFOM capability may be identification informationindicating the possession of the capability of establishing the firstPDN connection. In other words, the NBIFOM capability may beidentification information indicating that a gateway supports the NBIFOMfunction. That is, the existence of the NBIFOM capability in the storagemay mean that the PGW 30 is a gateway having the function ofestablishing the first PDN connection. In other words, the existence ofthe NBIFOM capability in the storage may mean that the PGW 30 is agateway supporting the NBIFOM function.

2.3. Description of Initial State

An initial state in the present embodiment will be described. Theinitial state in the present embodiment may be a first initial state ora second initial state, both of which will be described later.

Note that the initial state in the present embodiment need not belimited to the first or second initial state.

2.3.1. Description of First Initial State

The first initial state will be described. In the first state, the UE 10has not established the first PDN connection with the core network 90.However, the UE 10 has already established the second PDN connection. Ingreater detail, the UE 10 has not established the first PDN connectionwith the PGW_A 1310. However, the UE 10 has established the second PDNconnection with the PGW_B 1320.

Note that the PGW_A 1310 may be a gateway device selected by using theAPN 1. The PGW_B 1320 may be a gateway device selected by using the APN2. Moreover, the PGW_A 1310 and the PGW_B 1320 may be the PGW 30.Furthermore, the selection of gateway using the APN 1 and/or the APN 2may be performed by the TWAG 74 included and arranged in the accessnetwork B and/or the MME 40 included and arranged in the core network90.

In addition, the gateway device selected by using the APN 1 and thegateway device selected by using the APN 2 may be the same gatewaydevice. In this case, the PGW_A 1310 and the PGW_B 1320 may be the samedevice.

Note that the second PDN connection may be constituted of a transferpath between the UE 10 and the PGW 30 through the access network B.Thus, the first PDN connection may be constituted of a transfer paththat is a combination of a transfer path between the UE 10 and the TWAG74 and a transfer path between the TWAG 74 and the PGW_B 1320. Here, thetransfer path may be a bearer.

As described above, in the first state early stage, the UE 10 may be ina state of being connected to the core network 90 via the access networkB.

Note that the UE 10 need not be connected to the core network 90 via theaccess network A. In other words, the UE 10 need not perform an attachthrough the LTE access network.

Alternatively, the UE 10 may be in a state of being connected to thecore network 90 via the access network A. In this case, the UE 10 mayperform an Attach procedure initiated by the UE 10 to establish a thirdPDN connection.

Note that the third PDN connection may be established with the gatewayselected by using the APN 2. Alternatively, the third PDN connection maybe established with a gateway selected by using an APN different fromthe APN 1 and the APN 2.

The first initial state has been described above; however, the firstinitial state is not limited the above-described state, and only needsto be a state in which the multi-access PDN connection based on theNBIFOM has not been established through the access network B, forexample.

2.3.2. Description of Procedure for Leading to First Initial State

A procedure for leading to the first initial state will be describedwith reference to FIG. 15. In the procedure for leading to the firstinitial state, at least an Attach procedure to the core network 90through the access network B, illustrated in (A) of FIG. 15, isperformed. The first initial state is a state after at least the Attachprocedure to the core network 90 through the access network B,illustrated in (A) of FIG. 15, is performed.

Next, details of the Attach procedure to the core network 90 through theaccess network B will be described. The UE 10 first performsauthentication for accessing the access network B and the core network90 and a security association procedure for establishing a securityassociation for transmitting and/or receiving a message with the corenetwork 90 (S1502).

More specifically, the UE 10 performs an authentication procedure foraccessing the TWAG 74 arranged in the access network B and the PGW 30arranged in the core network 90. Upon the completion of theauthentication procedure, the UE 10 performs a procedure forestablishing security associations between the UE 10 and the TWAG 74 andbetween the TWAG 74 and the PGW 30. In the authentication procedure andthe procedure for establishing security associations, the UE 10 maytransmit control information including an Access Point Name (APN) to thecore network 90. The procedures for authentication and for establishingsecurity associations may be performed in accordance with an EAP orother techniques. The UE 10 can obtain the authentication for accessingthe PGW 30 selected by the TWAG 74 using the APN.

Furthermore, the UE 10 may transmit multiple APNs. For example, bytransmitting APN 1 and APN 2, the UE 10 can obtain the authenticationfor accessing a PGW 30 selected by the TWAG 74 using the APN 1 and a PGW30 selected using the APN 2 upon completion of the procedures forauthentication and for establishing a security association.

Upon the establishment of the security association, the UE 10 performs aPDN connectivity procedure for establishing the second PDN connectionwith the core network 90 through the access network B (S1504). Ingreater detail, the UE 10 establishes, via the TWAG 74, the PDNconnection with the PGW_B 1320 arranged in the core network 90.

Specifically, the UE 10 transmits a PDN connectivity request to the TWAG74 and/or the network. The UE 10 may transmit the PDN connectivityrequest including the APN 2.

The TWAG 74 and/or the network receives the PDN connectivity requesttransmitted from the UE 10. The TWAG 74 and/or the network transmits aPDN connectivity accept to the UE 10 upon the reception of the PDNconnectivity request. The TWAG 74 and/or the network may transmit thePDN connectivity accept including APN 2.

The UE 10 receives the PDN connectivity accept transmitted from the TWAG74 and/or the network. The UE 10 transmits a PDN connectivity completeto the TWAG 74 and/or the network based on the PDN connectivity accept.

The TWAG 74 and/or the network receives the PDN connectivity completetransmitted from the UE 10.

2.3.2. Description of Second Initial State

The second initial state will be described. In the second initial state,the UE 10 has not established a connection with the core network 90. Inother words, the UE 10 has not established the first PDN connection andthe second PDN connection with the core network 90. In greater detail,the UE 10 has not established the first PDN connection with the PGW_A1310 included and arranged in the core network 90. Furthermore, the UE10 has not established the second PDN connection with the PGW_B 1320included and arranged in the core network 90.

Note that the PGW_A 1310 may be a gateway device selected by using theAPN 1. The PGW_B 1320 may be a gateway device selected by using the APN2. Furthermore, the selection of gateway using the APN 1 and/or the APN2 may be performed by the TWAG 74 included and arranged in the accessnetwork B and/or the MME 40 included and arranged in the core network90.

As described above, in the second initial state, the UE 10 may have noconnection with the core network 90. In other words, the UE 10 may be ina state of not being connected to the core network 90 through either theaccess network A or access network B. Therefore, the UE 10 may be in astate of not being established any PDN connection.

The second initial state has been described above; however, the secondinitial state is not limited to the above-described state, and onlyneeds to be a state in which the connection to the core network 90through the access network B has not been established, for example.

2.3.3. Description of Procedure for Leading to Second Initial State

A procedure for leading to the second initial state will be describedwith reference to FIG. 15. In the procedure for leading to the secondinitial state, the procedure illustrated in a section (A) of FIG. 15 maynot be performed. In other words, the second initial state may be astate in which no particular procedures for making a connection with thecore network 90 through the access network B is not performed. In otherwords, the second initial state may be a state in which the UE 10 makesan initial connection to the core network 90 through the access networkB.

2.3.4. Description of Multi-Access PDN Connectivity EstablishmentProcedure

Next, an establishment procedure of the first PDN connection will bedescribed. Here, the initial state may be the first initial state or thesecond initial state. In the present embodiment, after the establishmentof the initial state, the UE 10 performs a PDN connectivity procedurefor establishing the first PDN connection with the core network 90through the access network B (S1506). In greater detail, the UE 10establishes, via the TWAG 74, the first PDN connection with the PGW_A1310 arranged in the core network 90.

Note that the first PDN connection may be constituted of a transfer paththat is a combination of a transfer path between the UE 10 and the TWAG74 and a transfer path between the TWAG 74 and the PGW_A 1310. Here, thetransfer path may be a bearer.

As illustrated in FIG. 15, the procedure for establishing the first PDNconnection may be a PDN connectivity procedure using the APN 1.

A specific example of the PDN connectivity procedure will be describedbelow.

2.4. Examples of PDN Connectivity Procedure

Examples of the PDN connectivity procedure for establishing the firstPDN connection will be described with reference to FIG. 16.

2.4.1. Example of First PDN Connectivity Procedure

An example of the first PDN connectivity procedure will be describedwith reference to FIG. 16.

As illustrated in (B) of FIG. 16, the UE 10 first performs theauthentication and the security association procedure for establishingthe security association. Note that the UE 10 may perform the securityassociation procedure in a case that its initial state is the secondinitial state. In other words, in a case that the initial state is thefirst initial state, the UE 10 need not perform the security associationprocedure. In this way, in the case that the initial state is the firstinitial state, the UE 10 may omit the security association procedurebecause the security association has already been established.

Note that the security association procedure performed by the UE 10 maybe similar to the security association procedure described withreference to (A) of FIG. 15. Therefore, detailed description of theprocedure is omitted.

Next, the UE 10 transmits a PDN connectivity request to the TWAG 74(S2102). The UE 10 may transmit the PDN connectivity request includingat least the PDN connectivity request message identity (PDN connectivityrequest message ID), the Procedure transaction identity (proceduretransaction ID), the Request type, and the PDN type. Furthermore, the UE10 may include at least first identification information and/or fifthidentification information and/or eighth identification information inthe PDN connectivity request. Moreover, the UE 10 may include the accesspoint name (APN) and/or protocol configuration options (PCOs) and/or thetraffic flow templates (TFTs) in the PDN connectivity request. Note thatthe UE 10 may transmit the PCO including the first identificationinformation and/or fifth identification information and/or eighthidentification information and/or the TFT.

Here, the first identification information may be the UE NBIFOMcapability representing that the UE 10 supports the NBIFOM. Note thatthe NBIFOM capability may be information indicating the provision of thefunction of establishing the multi-access PDN connection based on theNBIFOM.

Furthermore, the fifth identification information may be the ModeIndication representing an NBIFOM operation mode for the multi-accessPDN connection whose establishment is requested by the UE 10. Note thatthe UE 10 may include the UE-Initiated mode or the Network-Initiatedmode in the fifth identification information.

As described above, the UE 10 may transmit the fifth identificationinformation to request a mode of the multi-access PDN connection. Inother words, the UE 10 may transmit the fifth identification informationto request the establishment of the multi-access PDN connectioncorresponding to the mode indicated by the fifth identificationinformation. Note that the mode indicated by the fifth identificationinformation may be selected by the UE 10.

Note that, the UE 10 may be configured to transmit the fifthidentification information in a case of requesting the establishment ofthe multi-access PDN connection in the UE-Initiated mode, and may beconfigured not to transmit the fifth identification information in acase of requesting the establishment of the multi-access PDN connectionin the Network-Initiated mode.

Furthermore, the eighth identification information may be informationindicating a default access (Default Assess) in the multi-access PDNconnection. The eighth identification information may be informationindicating the 3GPP access or the WLAN access. The 3GPP access may be anaccess system that is not the WLAN access. More specifically, the 3GPPaccess may be information indicating an access network including theE-UTRAN access, the UTRAN access, and the GERAN access.

Alternatively, the eighth identification information may include moredetailed information. For example, the eighth identification informationmay be one of the E-UTRAN access, the UTRAN access and the GERAN access.

As described above, the UE 10 may transmit the eighth identificationinformation to request a default access for the multi-access PDNconnection. In other words, the UE 10 may transmit the eighthidentification information to request the establishment of themulti-access PDN connection in which the access network indicated by theeighth identification information is used in the default access.

Note that the access network indicated by the eighth identificationinformation may be selected by the UE 10. Furthermore, the UE 10 mayselect the access network indicated by the eighth identificationinformation based on operator policy such as Inter System Routing Policy(ISRP) received from an Access Network Discovery and Selection Function(ANDSF) server. More specifically, the UE 10 may select the accessnetwork indicated by the eighth identification information based onpriority information of the access network of the ISRP received from theANDSF server. For example, since the ISRP indicates that a higherpriority is given to a WLAN, the UE 10 may set information indicatingthe WLAN as the eighth identification information. Note that the UE 10may select the access network indicated by the eighth identificationinformation based on the ISRP, only in a case where the ISRP is valid oractive.

Note that, the UE 10 may be configured to transmit the eighthidentification information when requesting the establishment of themulti-access PDN connection in the UE-Initiated mode, and may beconfigured not to transmit the eighth identification information whenrequesting the establishment of the multi-access PDN connection in theNetwork-Initiated mode.

Furthermore, the UE 10 may be configured to transmit the eighthidentification information in a case where a default bearer has not beenestablished for the multi-access PDN connection, the establishment ofwhich is to be requested, and may be configured not to transmit theeighth identification information in a case where the default bearer hasalready been established for the multi-access PDN connection.

More specifically, the UE 10 may be configured to transmit the eighthidentification information when establishing a new multi-access PDNconnection, and may be configured not to transmit the eighthidentification information when adding a transfer path in a state inwhich the default bearer is established for the multi-access PDNconnection through the LTE access network.

As described above, the UE 10 may make a request for establishing themulti-access PDN connection by transmitting the first identificationinformation and/or the fifth identification information and/or theeighth identification information. In other words, the firstidentification information and/or the fifth identification informationand/or the eighth identification information may be informationindicating the request for establishing a multi-access PDN connection.

The PDN connectivity request message ID may be a message typerepresenting the PDN connectivity request message.

The procedure transaction ID may be information for identifying the PDNconnectivity procedure.

The APN may be an APN, to which the UE 10 requests a connection. Morespecifically, the APN may be the APN 1. The UE 10 may include the APN 1,in order to establish the multi-access PDN connection based on theNBIFOM. Here, the APN 1 may be an APN that is allowed to establish themulti-access PDN connection based on the NBIFOM and/or an APN that isallowed to perform communication based on the NBIFOM.

The request type may be information for identifying the type of the PDNconnectivity procedure to be requested. For example, since the UE 10performs an initial connection by using the APN 1, the request type maybe the type indicating an attach, rather than the type indicating ahandover.

The PDN type may indicate an available IP version. For example, the PDNtype may be IPv4, IPv6, or IPv4v6. The PCO may be protocol informationassociated with the PDN connection. Furthermore, the PCO may includeidentification information on the request. Note that the UE 10 maytransmit the PCO including the first identification information and/orfifth identification information and/or the eighth identificationinformation.

The TFT may be information for identifying an IP flow for performingcommunication by using the PDN connection established in the current PDNconnectivity procedure. Note that the IP flow to be identified may varyfor each application. Thus, the TFT identifies user data of a certainapplication.

More specifically, the TFT may be constituted of a five-tuple, or may beconstituted of identification information such as the application ID.Note that the five-tuple may be constituted of a combination of one ormore of a transmission-source IP address, a transmission-destination IPaddress, a transmission-source port number, a transmission-destinationport number, and a protocol number.

Note that in the present example, when transmitting the PDN connectivityrequest, the UE 10 does not request a certain NBIFOM operation mode, andthus, the UE 10 may transmit the PDN connectivity request withoutincluding the TFT. In other words, when the UE 10 requests theestablishment of the multi-access PDN connection based on the NBIFOMwithout requesting a certain NBIFOM operation mode, the UE 10 maytransmit the PDN connectivity request without including the TFT. Morespecifically, when the UE 10 includes the first identificationinformation and/or fifth identification information and/or eighthidentification information, the UE 10 may transmit the PDN connectivityrequest without including the TFT. Note that conventionally, the UE 10is capable of transmit the PCO including information indicating an IFOMsupport. Here, the IFOM support is identification informationrepresenting that the IP Flow Mobility (IFOM) is supported. Furthermore,the IFOM is a technique for switching a communication path of a certainIP flow by using the Dual Stack Mobile IPv6 (DSMIPv6) protocol. Thus,including the information indicating the IFOM support in the PCO allowsthe UE 10 to switch the access network through which the communicationof a certain IP flow is performed.

In the present embodiment, in a case where the UE 10 includes the firstidentification information and/or the fifth identification informationand/or the eighth identification information in the PCO, the UE 10 doesnot include the IFOM support. In contrast, in a case where the UE 10includes the IFOM support in the PCO, the UE 10 does not include thefirst identification information and/or the fifth identificationinformation and/or the eighth identification information. As describedabove, it may be possible to not configure both the first identificationinformation and/or fifth identification information and/or eighthidentification information and the IFOM support to be effective toensure a clear distinction between the use of the switching of thecommunication path based on the NBIFOM and the use of the switching ofthe communication path based on the IFOM.

Thus, the UE 10 is capable of establishing either the PDN connectionsupporting the IFOM or the PDN connection supporting the NBIFOM, in theestablishment procedure of a single PDN connection. In other words, thesingle PDN connection is any one of the PDN connection supporting theNBIFOM, the PDN connection supporting the IFOM, or the single-access PDNconnection.

The TWAG 74 receives the PDN connectivity request transmitted from theUE 10. Upon the reception of the PDN connectivity request and/or basedon the first identification information and/or fifth identificationinformation and/or eighth identification information included in the PDNconnectivity request, the TWAG 74 transmits a Create Session Request tothe PGW 30 (S2104).

Upon the reception of the PDN connectivity request and/or based on thefirst identification information and/or fifth identification informationand/or eighth identification information included in the PDNconnectivity request, the TWAG 74 may transmit the Create SessionRequest including at least the first identification information and/orfifth identification information and/or eighth identificationinformation. Furthermore, the TWAG 74 may include the TFT in the CreateSession Request, upon the reception of the TFT transmitted from the UE10.

Note that, the TWAG 74 may be configured to transmit the eighthidentification information in a case of requesting the establishment ofthe multi-access PDN connection in the UE-Initiated mode, and not totransmit the eighth identification information in a case of requestingthe establishment of the multi-access PDN connection in theNetwork-Initiated mode.

Furthermore, the TFT may be information for identifying an IP flow thatperforms communication by using the PDN connection established in thecurrent PDN connectivity procedure. Note that the IP flow to beidentified may vary for each application. Thus, the TFT identifies userdata of a certain application.

More specifically, the TFT may be constituted of a five-tuple, or may beconstituted of identification information such as the application ID.Note that the five-tuple may be constituted of a combination of one ormore of a transmission-source IP address, a transmission-destination IPaddress, a transmission-source port number, a transmission-destinationport number, and a protocol number.

Note that in a case that none of the first identification informationand/or fifth identification information and/or eighth identificationinformation is included in the PDN connectivity request, the TWAG 74 maytransmit the Create Session Request without including the firstidentification information and fifth identification information and/oreighth identification information. Moreover, in the case that the firstidentification information and/or fifth identification informationand/or eighth identification information is not included in the PDNconnectivity request, the TWAG 74 may perform a procedure forestablishing the single-access PDN connection.

The PGW 30 receives the Create Session Request transmitted from the TWAG74. Upon the reception of the Create Session Request, and/or based onthe first identification information and/or fifth identificationinformation and/or eighth identification information included in theCreate Session Request, the PGW 30 may perform an IP-CAN session updateprocedure with the PCRF 60.

Upon the reception of the Create Session Request and/or based on thefirst identification information and/or fifth identification informationand/or eighth identification information included in the Create SessionRequest, the PGW 30 may perform the IP-CAN session update procedureincluding at least the first identification information and/or fifthidentification information and/or eighth identification information.

Note that the PGW 30 may perform the IP-CAN session update procedure tonotify the PCRF 60 of information on the UE 10 and/or TWAG 74.

The PGW 30 may transmit, to the PCRF 60, a control message in the IP-CANsession procedure, including information indicating whether the PDNconnection to be established is the multi-access PDN connection based onthe NBIFOM or the single-access PDN connection, and/or the fifthidentification information, and/or the eighth identificationinformation.

More specifically, when the multi-access PDN connection based on theNBIFOM is to be established, the PGW 30 transmits, to the PCRF 60, theinformation indicating the access network B, the PDN connection ID, theinformation indicating that the PDN connection is the multi-access PDNconnection based on the NBIFOM, and the first identification informationand/or the fifth identification information and/or the eighthidentification information. Alternatively, when the single-access PDNconnection is to be established, the PGW 30 transmits, to the PCRF 60,the information indicating the access network B, the PDN connection ID,and the information indicating that the PDN connection is thesingle-access PDN connection.

Note that the PDN connection ID may be an ID assigned when the PGW 30establishes the PDN connection in the PDN connectivity procedure, or maybe information for uniquely identifying the PDN connection that the UE10 establishes with the PGW 30.

Furthermore, upon the reception of the first identification informationand/or fifth identification information and/or eighth identificationinformation, the PCRF 60 may transmit, to the PGW 30, a control messagein the IP-CAN session update procedure with the PGW 30, the controlmessage including at least the second identification information and/orseventh identification information and/or ninth identificationinformation. The detailed description of the second identificationinformation and/or the seventh identification information and/or theninth identification information will be described later.

Note that the PCRF 60 may perform the IP-CAN session update procedure tonotify the PGW 30 of the charging information and/or the QoS controlinformation and/or the routing information.

Upon the reception of the Create Session Request or the completion ofthe IP-CAN session update procedure, and/or based on the firstidentification information and/or fifth identification informationand/or eighth identification information included in the Create SessionRequest, and/or based on the second identification information and/orseventh identification information and/or ninth identificationinformation included in the IP-CAN session update procedure, the PGW 30transmits a Create Session Response to the TWAG 74 (S2106).

Upon the reception of the Create Session Request or the completion ofthe IP-CAN session update procedure, and/or based on the firstidentification information and/or fifth identification informationand/or eighth identification information included in the Create SessionRequest, and/or based on the second identification information and/orseventh identification information and/or ninth identificationinformation included in the IP-CAN session update procedure, the PGW 30transmits the Create Session Response including at least the secondidentification information and/or seventh identification informationand/or ninth identification information.

Furthermore, the PGW 30 may include the PDN Address and/or the PDNconnection ID and/or the TFT and/or the bearer identificationinformation identifying the default bearer in the Create SessionResponse.

Note that a method by which the PGW 30 acquires the secondidentification information and/or seventh identification informationand/or ninth identification information is not limited to theabove-described method for acquiring the seventh identificationinformation from the PCRF 60 in the IP-CAN session update procedure, andanother example may be employed. For example, the PGW 30 may create thesecond identification information and/or seventh identificationinformation and/or ninth identification information and transmit theCreate Session Response including the second identification informationand/or seventh identification information and/or ninth identificationinformation, without acquiring from the PCRF 60 in the IP-CAN sessionupdate procedure.

Here, the second identification information may be the NBIFOM capabilityrepresenting that the network supports the NBIFOM. Note that the NBIFOMcapability may be information indicating the provision of the functionof establishing the multi-access PDN connection.

Here, the seventh identification information may be the Allowed Moderepresenting the NBIFOM operation mode that is allowed for themulti-access PDN connection based on the NBIFOM to be established. Inother words, the seventh identification information may be the operationmode allowed by the operator.

As described above, the UE 10 may transmit the seventh identificationinformation to make a notification of the mode of the multi-access PDNconnection. In other words, the UE 10 may transmit the seventhidentification information to permit the establishment of themulti-access PDN connection corresponding to the mode indicated by theseventh identification information. Note that the mode indicated by theseventh identification information may be selected by the PCRF 60 or thePGE 30. Note that the PCRF 60 or the PGE 30 may transmit the modeindicated by the fifth identification information as the seventhidentification information, in a case where the PCRF 60 or the PGE 30allows the establishment of the multi-access PDN connection in the modeindicated by the fifth identification information requested by the UE10.

Note that the PCRF 60 or the PGW 30 may determine the Allowed Mode andthe seventh identification information based on the operator policy. Forexample, a policy that allows the establishment of only the PDNconnection of the UE-Initiated mode, a policy that allows theestablishment of only the PDN connection of the Network-Initiated mode,a policy that allows the establishment of both modes, a policy thatprohibits the establishment of both modes, and the like may be managed.

Note that the PCRF 60 or the PGW 30 may acquire the operator policy fromthe HSS 50 or the like. Alternatively, an operator policy created by anadministrator may be stored.

In addition, for the operator policy, a policy different for eachsubscriber may be managed. Alternatively, a policy different for eachAPN may be managed. For example, for each APN, a different Allowed Modefor the PDN connection to be established may be managed.

On the basis of the Allowed Mode, the PCRF 60 or the PGW 30 may includethe allowed operation mode in the seventh identification information.

In other words, when only the Network-Initiated mode is allowed, thePCRF 60 or the PGW 30 may include the Network-Initiated mode in theseventh identification information. Alternatively, when only theUE-Initiated mode is allowed, the PCRF 60 or the PGW 30 may include theUE-Initiated mode in the seventh identification information.

Note that when both the UE-Initiated mode and the Network-Initiated modeare allowed, the seventh identification information may include both theoperation modes. Alternatively, when both the UE-Initiated mode and theNetwork-Initiated mode are allowed and a default operation mode isconfigured, the seventh identification information may include only thedefault operation mode. Note that which one of the UE-Initiated mode andthe Network-Initiated mode is defined as the default operation mode maybe configured based on the operator policy.

Note that, when none of the operation modes is allowed for establishmentof the PDN connection, the PCRF 60 may transmit, to the PGW 30, thecause information indicating that the requested operation mode is notallowed.

When none of the operation modes is allowed for establishment of the PDNconnection, the PGW 30 need not notify the TWAG 74 of the seventhidentification information.

When none of the operation modes is allowed for establishment of the PDNconnection, the PGW 30 may transmit, to the TWAG 74, the Create SessionResponse including the cause information indicating that the requestedoperation mode is not allowed.

When none of the operation modes is allowed for establishment of the PDNconnection, the PGW 30 may notify the TWAG 74 that there is no allowedoperation.

As described above, on the basis of the Allowed Mode, the PCRF 60 or thePGW 30 may regard an operation mode that is allowed for establishment ofthe PDN connection as the seventh identification information.

Note that when the Network-Initiated mode is not included in the seventhidentification information, the PCRF 60 need not transmit the TFT to thePGW 30.

In other words, note that only when the Network-Initiated mode isincluded in the seventh identification information, the PCRF 60 maytransmit the TFT to the PGW 30.

Note that when the Network-Initiated mode is not included in the seventhidentification information, the PGW 30 need not transmit the TFT to theTWAG 74. Thus, in this case, the PGW 30 need not include either the TFTor the PDN address in the Create Session Response.

In other words, note that only when the Network-Initiated mode isincluded in the seventh identification information, the PGW 30 maytransmit the TFT to the TWAG 74. Thus, in this case, the PGW 30 mayinclude the TFT and the PDN address (PDN Address) in the Create SessionResponse.

The PDN address may be an IP address assigned to the UE 10. For example,the PDN address may be an IPv4 address, or an IPv6 prefix and aninterface ID for constituting an IPv6 address. Here, the PGW 30 mayassign the IP address of the UE 10. Moreover, the PGW 30 may include theIP address assigned to the UE 10 in the PDN address.

Furthermore, the PDN connection ID may be information for uniquelyidentifying the PDN connection established between the UE 10 and the PGW30.

The PDN connection ID may be assigned by the PGW 30, or may be assignedby the TWAG 74. In other words, the PGW 30 may assign the PDN connectionID.

Furthermore, the ninth identification information may be informationindicating a default access (Default Assess) in the multi-access PDNconnection. Note that the ninth identification information may beinformation indicating the 3GPP access or the WLAN access. The 3GPPaccess may be an access system that is not the WLAN access. Morespecifically, the 3GPP access may be information indicating an accessnetwork including the E-UTRAN access, the UTRAN access, and the GERANaccess.

Alternatively, the ninth identification information may include moredetailed information. For example, the ninth identification informationmay be one of E-UTRAN access, UTRAN access and GERAN access.

As described above, the PCRF 60 or the PGE 30 may transmit the ninthidentification information to notify the UE 10 of the default access forthe multi-access PDN connection. In other words, the PCRF 60 or the PGE30 may transmit the ninth identification information to request theestablishment of the multi-access PDN connection in which the accessnetwork indicated by the ninth identification information is used as thedefault access. Note that the access network indicated by the ninthidentification information may be selected by the PCRF 60 or the PGE 30.Note that the PCRF 60 or the PGE 30 may transmit the access networkindicated by the eighth identification information as the ninthidentification information, in a case where the PCRF 60 or the PGE 30allows the establishment of the multi-access PDN connection for thedefault access indicated by the eighth identification informationrequested by the UE 10.

As described above, the establishment of the multi-access PDN connectionis permitted by transmitting the second identification informationand/or the seventh identification information and/or the ninthidentification information. In other words, the second identificationinformation and/or the seventh identification information and/or theninth identification information may be information indicating that themulti-access PDN connection is to be established or establishment of themulti-access PDN connection is permitted.

Note that, the PCRF 60 and the PGW 30 may be configured to transmit theninth identification information in a case where a default bearer hasnot been established for the multi-access PDN connection, theestablishment of which is to be requested, and may be configured not totransmit the ninth identification information in a case where thedefault bearer has already been established for the multi-access PDNconnection.

More specifically, the PCRF 60 and the PGW 30 may be configured totransmit the ninth identification information when establishing a newmulti-access PDN connection, and not to transmit the ninthidentification information when adding a transfer path in a state inwhich the default bearer is established for the multi-access PDNconnection through the LTE access network.

The TWAG 74 receives the Create Session Response transmitted from thePGW 30. Upon the reception of the Create Session Response and/or basedon the second identification information and/or seventh identificationinformation and/or ninth identification information included in theCreate Session Response, the TWAG 74 transmits a PDN connectivity acceptto the UE 10 (S2108). Note that the PDN connectivity accept message maybe any control message indicating that establishment of a PDN connectionis allowed, and may be any Activate default EPS bearer context request.The PDN connectivity accept message may be a response message to the PDNconnectivity request.

Upon the reception of the Create Session Response and/or based on thesecond identification information and/or seventh identificationinformation and/or ninth identification information included in theCreate Session Response, the TWAG 74 may transmit the PDN connectivityaccept including at least a PDN connectivity accept message identity(PDN connectivity accept message ID), the Procedure transaction ID, theAPN, the PDN address (PDN Address), the PDN connection ID, and the userplane connection ID (User Plane Connection ID). Furthermore, the TWAG 74may include at least the second identification information and/orseventh identification information and/or ninth identificationinformation in the PDN connectivity accept. Moreover, the TWAG 74 mayinclude the PCO and/or the Cause and/or the TFT and/or the beareridentification information identifying the default bearer, and/or thePDN connection attribute information, in the PDN connectivity accept.Note that the TWAG 74 may transmit the PCO including the secondidentification information and/or seventh identification informationand/or ninth identification information and/or the TFT.

Here, the PDN connectivity accept message ID may be a message typerepresenting the PDN connectivity accept message.

The APN may be an APN, to which the UE 10 is allowed to connect. Morespecifically, the APN may be the APN 1. The APN 1 may be an APN that isallowed to establish the multi-access PDN connection based on theNBIFOM. The TWAG 74 may include the APN 1 in the PDN connectivityaccept.

The PDN address may be an IP address assigned to the UE 10. For example,the PDN address may be an IPv4 address, or an interface ID forconstituting an IPv6 address.

The PDN connection ID may be information for uniquely identifying thePDN connection established between the UE 10 and the PGW 30. The PDNconnection ID may be an ID assigned by the PGW 30, or an ID assigned bythe TWAG 74. In other words, the TWAG 74 may assign the PDN connectionID.

The user plane connection ID is information for identifying a userplane. The user plane is a transfer path used for transferring user datain the PDN connection. The TWAG 74 may assign the user plane connectionID.

The Cause may be information representing that the PDN type of the PDNaddress assigned to the UE 10 is different from the PDN type requestedby the UE 10 in the PDN connectivity request.

Note that the TWAG 74 and/or the PGW 30 may include the secondidentification information and/or the seventh identification informationand/or the ninth identification information in the PCO. However, in acase where the TWAG 74 and/or the PGW 30 includes the secondidentification information and/or the seventh identification informationand/or the ninth identification information in the PCO, the TWAG 74and/or the PGW 30 does not include the IFOM support. In contrast, in acase where the TWAG 74 and/or the PGW 30 includes the IFOM support inthe PCO, the TWAG 74 and/or the PGW 30 does not include the secondidentification information and/or the seventh identification informationand/or the ninth identification information. As described above, it maybe possible to not configure both the second identification informationand/or seventh identification information and/or ninth identificationinformation and the IFOM support to be effective to ensure a cleardistinction between the use of the switching of the communication pathbased on the NBIFOM and the use of the switching of the communicationpath based on the IFOM.

The PDN connection attribute information may be information indicatingthat the PDN connection established in the present PDN connectivityprocedure is the multi-access PDN connection, and/or informationindicating that user data transmitted and/or received by using the PDNconnection established in the PDN connection the present PDNconnectivity procedure is allowed to be transmitted and/or receivedthrough the access network A and the access network B, and/or if thereis only one operation mode indicated by the seventh identificationinformation, information indicating that the PDN connection establishedin the present PDN connectivity procedure is the multi-access PDNconnection based on the NBIFOM of the operation mode indicated by theseventh identification information.

Note that the UE 10 may transmit the PDN connectivity accept messagethat further includes the connectivity type indicating the type of thePDN connection and/or the WLAN offload permission information (WLANoffload acceptablity) indicating whether the WLAN offload can beperformed. Furthermore, the TWAG 74 may transmit the connectivity typeor the WLAN offload permission information including the PDN connectionattribute information.

The UE 10 receives the PDN connectivity accept transmitted from the TWAG74. Upon the reception of the PDN connectivity accept and/or based onthe second identification information and/or seventh identificationinformation and/or ninth identification information included in the PDNconnectivity accept, the UE 10 transmits a PDN connectivity complete tothe TWAG 74 (S2110).

The UE 10 may transmit the PDN connectivity complete including at leasta PDN connectivity complete message ID (PDN connectivity complete), theprocedure transaction ID, and the PDN connection ID.

Furthermore, when multiple INFOM operation modes are included in theseventh identification information, the UE 10 may include at least thefifth identification information in the PDN connectivity complete. Inother words, when multiple INFOM operation modes are allowed, the UE 10may select one of the allowed modes and transmit the fifthidentification information including the selected mode.

Here, the fifth identification information may be the Mode Indicationrepresenting an NBIFOM operation mode for the multi-access PDNconnection whose establishment is requested by the UE 10. Note that theUE 10 may include the UE-Initiated mode or the Network-Initiated mode inthe fifth identification information.

Specifically, when the UE-Initiated mode and the Network-Initiated modeare included in the seventh identification information included in thePDN connectivity accept, the UE 10 may include the UE-Initiated mode orthe Network-Initiated mode in the fifth identification information.

Which of the UE-Initiated mode and the Network-Initiated mode is to beincluded in the fifth identification information may be determined basedon a UE policy. Note that the UE policy may be any informationconfigured for the UE 10. For example, the UE policy may be informationconfigured by a user.

The PDN connectivity complete message ID may be a message typerepresenting the PDN connectivity complete message.

After the fourth PDN connectivity procedure is completed, the UE 10 andthe PGW 30 establish the first PDN connection of the operation modedetermined on the basis of the operator policy. Alternatively, the UE 10establishes the first PDN connection of an operation mode selected fromthe operation modes allowed based on the operator policy. Note that uponthe reception of the PDN connectivity accept and/or on the basis of thePDN connection attribute information and/or the seventh identificationinformation and/or the operation mode selected on the basis of theseventh identification information, the UE 10 may identify the NBIFOMoperation mode for the established PDN connection. Upon theestablishment of the first PDN connection, the UE 10 and the PGW 30determine a PDN connection and/or a transfer path, such as an EPSbearer, for transmitting and/or receiving the IP flow by using the TFT,and transmit and/or receive user data corresponding to the IP flowidentified by the TFT. More specifically, the UE 10 and the PGW 30transmit and/or receive a flow identified by the TFT by using the firstPDN connection.

Furthermore, in the establishment of the first PDN connection, the UE 10and the PGW 30 establish a default bearer. The UE 10 and the PGW 30store the identification information of the default bearer establishedin the PDN connectivity procedure and the information identifying theWLA access network in association with each other, in response to thecompletion of the PDN connectivity procedure through the WLAN accessnetwork.

Note that the UE 10 performs data transmission and/or reception usingthe default bearer when the UE 10 does not receive the TFT or transmitsand/or receives the user data not matching the held TFT. In addition,the PGW 30 performs data transmission and/or reception using the defaultbearer when the PGW 30 does not receive the TFT or transmits and/orreceives the user data not matching the held TFT.

In this way, the UE 10 and the PGW 30 establish a multi-access PDNconnection in the PDN connectivity procedure, and establish a defaultbearer for the multi-access PDN connection. Furthermore, the UE 10 andthe PGW 30 are capable of storing a default access for selecting adefault bearer in association with the multi-access PDN connection, in acase where multiple default bearers are established.

Note that in the example of the first PDN connectivity procedure, a casehas been described in which the transmission and/or reception of the TFTis included in the PDN connectivity procedure; however, the first PDNconnectivity procedure is not limited to this case. The transmissionand/or reception of the TFT may be performed after the multi-access PDNconnection based on the NBIFOM is established.

Therefore, the UE 10 and the TWAG 74 may perform transmission and/orreception without including the TFT in the PDN connectivity requestand/or the PDN connectivity response (PDN connectivity accept), andestablish the multi-access PDN connection based on the NBIFOM. In otherwords, at a point in time when the PDN connection is established, theremay be no IP flow transmitting and/or receiving user data by using thePDN connection. In this case, the UE 10 and the TWAG 74 transmit the TFTafter the multi-access PDN connection based on the NBIFOM isestablished.

More specifically, when the PDN connection of the UE-Initiated mode isestablished, the UE 10 may transmit the TFT to the TWAG 74. In addition,the TWAG 74 receives the TFT from the UE 10 and transmits the TFT to thePGW 30. Thus, the UE 10 and the PGW 30 are capable of determining a PDNconnection and/or a transfer path such as an EPS bearer for transmittingand/or receiving the IP flow by using the TFT, and are capable oftransmitting and/or receiving user data corresponding to the IP flowidentified by the TFT.

Note that the UE 10 and the PGW 30 perform data transmission and/orreception using the default bearer when the UE 10 and the PGW 30transmit and/or receive the user data not matching the held TFT.

On the other hand, when the PDN connection of the Network-Initiated modeis established, the PGW 30 may transmit the TFT to the TWAG 74. Here,the PGW 30 may receive, from the PCRF 60, the TFT determined on thebasis of the operator policy. In addition, the TWAG 74 receives the TFTfrom the PGW 30 and transmits the TFT to the UE 10. Thus, the UE 10 andthe PGW 30 are capable of determining a PDN connection and/or a transferpath such as an EPS bearer for transmitting and/or receiving the IP flowby using the TFT, and are capable of transmitting and/or receiving userdata corresponding to the IP flow identified by the TFT.

Note that the UE 10 and the PGW 30 perform data transmission and/orreception using the default bearer when the UE 10 and the PGW 30transmit and/or receive the user data not matching the held TFT.

Furthermore, in the example of the first PDN connectivity procedure, acase has been described in which the UE 10 and the PGW 30 establish thefirst PDN connection of an operation mode selected by the UE 10 from theoperation modes determined based on the operator policy or the operationmodes allowed based on the operator policy; however, the first PDNconnectivity procedure is not limited to this case. The UE 10 may rejectthe establishment of the first PDN connection.

For example, in a case that the UE 10 does not support the operationmode allowed based on the operator policy and/or in a case that theoperation mode allowed based on the operator policy does not comply withthe policy of the UE 10, the UE 10 may reject the establishment of thefirst PDN connection.

In greater detail, the UE 10 may transmit a PDN connectivity reject tothe TWAG 74, upon the reception of the PDN connectivity accept, and/oron the basis of the seventh identification information included in thePDN connectivity accept and/or the PDN connection attribute informationand/or the policy of the UE 10.

The UE 10 may transmit the PDN connectivity reject including at leastone or more of the PDN connectivity reject message identity (PDNconnectivity reject message ID), the procedure transaction ID, and theCause. Furthermore, the UE 10 may further include fourth identificationinformation in the PDN connectivity reject. Furthermore, the UE 10 mayfurther include the PCO and/or a Tw1 value in the PDN connectivityreject. Note that the UE 10 may transmit the PCO including the fourthidentification information.

The fourth identification information may be information representingthat the UE 10 does not support the operation mode allowed based on theoperator policy and/or information representing that the operation modeallowed based on the operator policy does not comply with the policy ofthe UE 10.

The PDN connectivity reject message ID may be a message typerepresenting the PDN connectivity reject message.

The Cause may be information representing a reason why the PDNconnectivity request is rejected. Here, the UE 10 may notify the UE 10of the fourth identification information included in the Cause.

The Tw1 value may be a value of Tw1 timer included in a case that Causerepresents insufficient resources.

The TWAG 74 may receive the PDN connectivity reject transmitted from theUE 10. Upon the reception of the PDN connectivity reject and/or based onthe fourth identification information included in the PDN connectivityreject, the TWAG 74 may delete the EPS bearer context, held by the TWAG74, relating to the established PDN connection. The TWAG 74 may transmitthe fourth identification information included in the PDN connectivityreject to the PGW 30.

The PGW 30 may receive the fourth identification information transmittedfrom the TWAG 74. Upon the reception of the fourth identificationinformation and/or on the basis of the operator policy, the PGW 30 maydelete the EPS bearer context, held by the PGW 30, relating to theestablished PDN connection.

Furthermore, the PGW 30 may perform the IP-CAN session update procedurewith the PCRF 60, upon the reception of the fourth identificationinformation. The PGW 30 may include the fourth identificationinformation in the IP-CAN session update procedure.

The PCRF 60 may change the operator policy on the basis of the IP-CANsession update procedure. Note that on the basis of the change of theoperator policy, the PGW 30 may delete the EPS bearer context, held bythe PGW 30, relating to the established PDN connection.

2.4.2. Description of State After PDN Connectivity EstablishmentProcedure

Performing the above-described first PDN connectivity procedure leads toa first state and a second state, both of which will be described later.

Note that an initial state in the additional Attach procedure may be thefirst state or the second state. The initial state in the additionalAttach procedure may not be limited to the first or second state.

2.4.3. Description of First State

The first state will be described with reference to FIG. 13. In thefirst state, the UE 10 has established the first PDN connection with thecore network 90. However, the UE 10 has not yet established the secondPDN connection. In greater detail, the UE 10 has established the firstPDN connection with the PGW_A 1310. However, the UE 10 has notestablished the second PDN connection with the PGW_B 1320.

Note that the PGW_A 1310 may be a gateway device selected by using theAPN 1. The PGW_B 1320 may be a gateway device selected by using the APN2. Moreover, the PGW_A 1310 and the PGW_B 1320 may be the PGW 30.Furthermore, the selection of gateway using the APN 1 and/or the APN 2may be performed by the TWAG 74 included and arranged in the accessnetwork B and/or the MME 40 included and arranged in the core network90.

In addition, the gateway device selected by using the APN 1 and thegateway device selected by using the APN 2 may be the same gatewaydevice. In this case, the PGW_A 1310 and the PGW_B 1320 may be the samedevice.

Note that the first PDN connection may be constituted of a transfer pathbetween the UE 10 and the PGW 30 through the access network B. Thus, thefirst PDN connection may be constituted of a transfer path that is acombination of a transfer path between the UE 10 and the TWAG 74 and atransfer path between the TWAG 74 and the PGW_A 1310. Here, the transferpath may be a bearer.

As described above, in the first state, the UE 10 may be in a state inwhich the multi-access PDN connection based on the NBIFOM is establishedvia the access network B. In addition, in the first state early stage,the UE 10 may be in a state of not being connected to the core network90 via the access network A.

Note that the UE 10 need not establish the single-access PDN connectionvia the access network B.

Alternatively, the UE 10 may be in a state in which the single-accessPDN connection is established via the access network B. In this case,the UE 10 performs, in the WLAN access network, the Attach procedure orthe PDN connectivity procedure in the single-access PDN connectioninitiated by the UE 10 to establish the third PDN connection.

Note that the third PDN connection may be established with the gatewayselected by using the APN 2. Alternatively, the third PDN connection maybe established with a gateway selected by using an APN different fromthe APN 1 and the APN 2.

The first state has been described above; however, the first state isnot limited to the above-described state, and only needs to be a statein which the multi-access PDN connection based on the NBIFOM has beenestablished through the access network B and the PDN connection has notbeen established through the access network A, for example.

2.4.4. Description of Second State

The second state will be described with reference to FIG. 14. In thesecond state, the UE 10 has established the first PDN connection withthe core network 90. Furthermore, the UE 10 has established the secondPDN connection with the core network 90. In greater detail, the UE 10has established the first PDN connection with the PGW_A 1310.Furthermore, the UE 10 has established the second PDN connection withthe PGW_B 1320.

Note that the PGW_A 1310 may be a gateway device selected by using theAPN 1. The PGW_B 1320 may be a gateway device selected by using the APN2. Moreover, the PGW_A 1310 and the PGW_B 1320 may be the PGW 30.Furthermore, the selection of gateway using the APN 1 and/or the APN 2may be performed by the TWAG 74 included and arranged in the accessnetwork B and/or the MME 40 included and arranged in the core network90.

In addition, the gateway device selected by using the APN 1 and thegateway device selected by using the APN 2 may be the same gatewaydevice. In this case, the PGW_A 1310 and the PGW_B 1320 may be the samedevice.

Note that the first PDN connection may be constituted of a transfer pathbetween the UE 10 and the PGW 30 through the access network B. Thus, thefirst PDN connection may be constituted of a transfer path that is acombination of a transfer path between the UE 10 and the TWAG 74 and atransfer path between the TWAG 74 and the PGW_B 1320. Here, the transferpath may be a bearer.

In addition, the second PDN connection may be constituted of a transferpath between the UE 10 and the PGW 30 through the access network A.Thus, the second PDN connection may be constituted of a transfer paththat is a combination of a transfer path between the UE 10 and theeNodeB 45, a transfer path between the eNodeB 45 and the SGW 35, and atransfer path between the SGW 35 and the PGW_B 1320. Here, the transferpath may be a bearer.

As described above, in the first state, the UE 10 may be in a state inwhich the multi-access PDN connection based on the NBIFOM is establishedvia the access network B. Furthermore, the UE 10 may be in a state inwhich the single-access PDN connection is established via the accessnetwork A.

Note that the UE 10 need not establish the single-access PDN connectionvia the access network B.

Alternatively, the UE 10 may be in a state in which the single-accessPDN connection is established via the access network B. In this case,the UE 10 performs, in the WLAN access network, the Attach procedure orthe PDN connectivity procedure in the single-access PDN connectioninitiated by the UE 10 to establish the third PDN connection.

Note that the third PDN connection may be established with the gatewayselected by using the APN 2. Alternatively, the third PDN connection maybe established with a gateway selected by using an APN different fromthe APN 1 and the APN 2.

The second state has been described above; however, the second state isnot limited to the above-described state, and only needs to be a statein which the multi-access PDN connection based on the NBIFOM has beenestablished through the access network B and the single-access PDNconnection has been established through the access network A, forexample.

2.5. Additional Attach Procedure

An additional Attach procedure will be described below. The Operationmode of the first PDN connection being the Network-initiated mode refersto, in other words, flow switching and/or update of the Routing Rule ofthe PDN connection initiated by the UE 10 being not possible. Incontrast, the PDN connectivity procedure and/or the Attach procedure isinitiated by the UE 10.

Note that the Routing Rule may be information for selecting a transferpath or bearer through which user data is transmitted and/or receivedbased on the TFT held by the UE 10. More specifically, the Routing Rulemay be information in which the TFT and the transfer path or bearer areassociated with each other.

As described above, the second state is a state in which the UE 10establishes the first PDN connection only through the access network B.That is, the transfer path through the LTE access network is notincluded in the first PDN connection. Note that the transfer path may bea bearer and/or a communication path.

Therefore, when the first PDN connection in the second state is in theNetwork-initiated mode, the network and/or the PCRF 60 cannot includethe transfer path through the access network A in the first PDNconnection.

Therefore, based on the state transition to the second state and thefact that the Operation mode is the Network-initiated mode, the UE 10may perform a procedure for establishing the transfer path through theaccess network A.

Moreover, also in a case that the Operation mode of the first PDNconnection in the first initial state and/or the second initial state isthe UE-initiated mode, the UE 10 may perform a procedure forestablishing the transfer path through the access network A. based onthe Routing Rule stored in the UE 10.

Specifically, the UE 10 may perform the procedure for adding a transferpath through the access network A to the first PDN connection in a casethat the Routing Rule of the first PDN connection indicates priority toan LTE access.

More specifically, the UE 10 may perform the procedure for adding atransfer path through the access network A in a case that the UE 10stores the Routing Rule in which a specific flow and an LTE access areassociated with each other for the first PDN connection.

In other words, the UE 10 does not perform the procedure for adding atransfer path through the access network A to the first PDN connectionin a case that the Routing Rule of the first PDN connection does notindicate priority to an LTE access.

More specifically, the UE 10 does not perform the procedure for adding atransfer path through the access network A in a case that the UE 10 doesnot store the Routing Rule in which a specific flow and an LTE accessare associated with each other for the first PDN connection.

Hereinafter, details of the procedure will be described.

2.5.1. Example of Second Additional Attach Procedure

Next, an example of a second additional Attach procedure will bedescribed. As illustrated in FIG. 17, the initial state of the presentexample of procedure is first initial state (S2302). Note that theprocedure for changing the state to the first initial state may besimilar to the procedure described above, and detailed description willbe omitted.

In the first initial state, the UE 10 only needs to have established thefirst PDN connection with the PGW 30 and/or the network through theaccess network A. Specifically, the first initial state is a state inwhich the UE 10 establishes the first PDN connection through the TWAG 74with the PGW_A selected using the APN 1. Note that the first PDNconnection may be the multi-access PDN connection based on the NBIFOM.

The UE 10 performs the Attach procedure through the access network Aupon transition to the first initial state and establishment of thefirst PDN connection in the Network-initiated mode (S2304).

The UE 10 may perform the Attach procedure through the access network Abased on transition to the first initial state in which the first PDNconnection in the UE-initiated mode is established and based on theRouting Rule.

Specifically, based on the Routing Rule giving priority to an LTEaccess, the UE 10 may perform the Attach procedure through the accessnetwork A.

Specifically, the UE 10 may perform the Attach procedure through theaccess network A in a case that the state is changed to the firstinitial state in which the first PDN connection in the UE-initiated modeis established and the Routing Rule of the first PDN connectionindicates priority to an LTE access.

More specifically, the UE 10 may perform the Attach procedure throughthe access network A in a case that the state is changed to the firstinitial state in which the first PDN connection in the UE-initiated modeis established and the UE 10 stores the Routing Rule in which a specificflow and an LTE access are associated with each other for the first PDNconnection.

In other words, the UE 10 does not perform the Attach procedure throughthe access network A in a case that the Routing Rule of the first PDNconnection does not indicate priority to an LTE access, even if thestate is changed to the first initial state in which the first PDNconnection in the UE-initiated mode is established.

More specifically, the UE 10 does not perform the Attach procedurethrough the access network A in a case that the UE 10 does not store theRouting Rule in which a specific flow and an LTE access are associatedwith each other for the first PDN connection, even if the state ischanged to the first initial state in which the first PDN connection inthe UE-initiated mode is established.

Note that the UE 10 may transmit the Attach Request including at leastthe APN and/or the PDN connection ID.

The APN may be an APN, to which the UE 10 requests a connection. Morespecifically, the APN may be the APN 2. The UE 10 may include the APN 2in order to establish the single-access PDN connection. Here, the APN 2may be an APN that is not allowed to establish the multi-access PDNconnection based on the NBIFOM and/or an APN that is not allowed toperform communication based on the NBIFOM.

That is, the UE 10 may request establishment of a single access PDNconnection, using different APN 2 from the APN 1 acquired from thenetwork when establishing the first PDN connection.

Furthermore, the PDN connection ID may be an ID assigned when the PGW 30establishes the PDN connection in the PDN connectivity procedure, or maybe information for uniquely identifying the PDN connection that the UE10 establishes with the PGW 30.

Note that in the Attach procedure, the UE 10 performs authentication andsecurity association procedure with the MME 40 and the PGW_A and thePGW_B.

In addition, the UE 10 may acquire an APN from the network in responseto the Attach procedure complete.

The APN may be an APN, to which the UE 10 requests a connection. Morespecifically, the APN may be the APN 2. The UE 10 may include the APN 2in order to establish the single-access PDN connection. Here, the APN 2may be an APN that is not allowed to establish the multi-access PDNconnection based on the NBIFOM and/or an APN that is not allowed toperform communication based on the NBIFOM.

That is, the UE 10 may establish a single access PDN connection, usingdifferent APN 2 from the APN 1 acquired from the network in response toestablishment of the first PDN connection.

Through above procedures, the UE 10 and the core network 90 changestheir states from the first initial state to the second initial state(S2306).

Next, the UE 10 performs the PDN connectivity procedure through theaccess network B upon transition to the second initial state andestablishment of the first PDN connection in the Network-initiated mode(S2308).

Alternatively, the UE 10 performs the PDN connectivity procedure throughthe access network A, upon transition to the second initial state andbased on the Routing Rule of the first PDN connection established in theUE-Initiated mode.

Specifically, based on the Routing Rule giving priority to an LTEaccess, the UE 10 may perform the Attach procedure through the accessnetwork A.

Specifically, the UE 10 may perform the procedure for adding a transferpath through the access network A to the first PDN connection in a casethat the state is changed to the second initial state in which the firstPDN connection in the UE-initiated mode is established and the RoutingRule of the first PDN connection indicates priority to an LTE access.

More specifically, the UE 10 may perform the procedure for adding atransfer path through the access network A in a case that the state ischanged to the second initial state in which the first PDN connection inthe UE-initiated mode is established and the UE 10 stores the RoutingRule in which a specific flow and an LTE access are associated with eachother for the first PDN connection.

In other words, the UE 10 may not perform the procedure for adding atransfer path through the access network A to the first PDN connectionin a case that the Routing Rule of the first PDN connection does notindicate priority to an LTE access, even when the state is changed tothe second initial state in which the first PDN connection in theUE-initiated mode is established.

More specifically, the UE 10 does not perform the procedure for adding atransfer path through the access network A in a case that the UE 10 doesnot store the Routing Rule in which a specific flow and an LTE accessare associated with each other for the first PDN connection, even whenthe state is changed to the second initial state in which the first PDNconnection in the UE-initiated mode is established.

A PDN connectivity procedure through an access network A will bedescribed with reference to FIG. 18.

The UE 10 first transmits a PDN connectivity request to the MME 40 viathe eNodeB 45 (S2402). The UE 10 may transmit the PDN connectivityrequest including at least the PDN connectivity request message identity(PDN connectivity request message ID), the Procedure transactionidentity (procedure transaction ID), the Request type, the PDN type, theProtocol discriminator, and EPS bearer identity (EPS bearer ID).Furthermore, the UE 10 may include at least first identificationinformation and/or fifth identification information and/or eighthidentification information and/or PDN connection ID in the PDNconnectivity request. Moreover, the UE 10 may include the access pointname (APN) and/or protocol configuration options (PCOs) and/or thetraffic flow templates (TFTs) in the PDN connectivity request. Note thatthe UE 10 may transmit the PCO including the first identificationinformation and/or fifth identification information and/or the eighthidentification information and/or the TFT and/or the PDN connection ID.

Here, the first identification information may be the UE NBIFOMcapability representing that the UE 10 supports the NBIFOM. Note thatthe NBIFOM capability may be information indicating the provision of thefunction of establishing the multi-access PDN connection based on theNBIFOM.

Note that, the UE 10 may be configured to transmit the fifthidentification information in a case of requesting the establishment ofthe multi-access PDN connection in the UE-Initiated mode, and may beconfigured not to transmit the fifth identification information in acase of requesting the establishment of the multi-access PDN connectionin the Network-Initiated mode.

Furthermore, the fifth identification information may be the ModeIndication representing an NBIFOM operation mode for the multi-accessPDN connection whose establishment is requested by the UE 10. Note thatthe UE 10 may include the UE-Initiated mode or the Network-Initiatedmode in the fifth identification information.

As described above, the UE 10 may transmit the fifth identificationinformation to request a mode of the multi-access PDN connection. Inother words, the UE 10 may transmit the fifth identification informationto request the establishment of the multi-access PDN connectioncorresponding to the mode indicated by the fifth identificationinformation. Note that the mode indicated by the fifth identificationinformation may be selected by the UE 10.

Furthermore, the eighth identification information may be informationindicating a default access (Default Assess) in the multi-access PDNconnection. The eighth identification information may be informationindicating the 3GPP access or the WLAN access. The 3GPP access may be anaccess system that is not the WLAN access. More specifically, the 3GPPaccess may be information indicating an access network including theE-UTRAN access, the UTRAN access, and the GERAN access.

Alternatively, the eighth identification information may include moredetailed information. For example, the eighth identification informationmay be one of the E-UTRAN access, the UTRAN access and the GERAN access.

Note that, the UE 10 may be configured to transmit the eighthidentification information when requesting the establishment of themulti-access PDN connection in the UE-Initiated mode, and may beconfigured not to transmit the eighth identification information whenrequesting the establishment of the multi-access PDN connection in theNetwork-Initiated mode.

Furthermore, the UE 10 may be configured to transmit the eighthidentification information in a case where a default bearer has not beenestablished for the multi-access PDN connection, the establishment ofwhich is to be requested, and may be configured not to transmit theeighth identification information in a case where the default bearer hasalready been established for the multi-access PDN connection.

More specifically, the UE 10 may be configured to transmit the eighthidentification information in a case of establishing a new multi-accessPDN connection, and may be configured not to transmit the eighthidentification information in a case of adding a transfer path in astate in which the default bearer is established for the multi-accessPDN connection through the WLAN access network.

As described above, the UE 10 may transmit the eighth identificationinformation to request a default access for the multi-access PDNconnection. In other words, the UE 10 may transmit the eighthidentification information to request the establishment of themulti-access PDN connection in which the access network indicated by theeighth identification information is used in the default access.

Note that the access network indicated by the eighth identificationinformation may be selected by the UE 10. Furthermore, the UE 10 mayselect the access network indicated by the eighth identificationinformation based on operator policy such as Inter System Routing Policy(ISRP) received from an Access Network Discovery and Selection Function(ANDSF) server. More specifically, the UE 10 may select the accessnetwork indicated by the eighth identification information based onpriority information of the access network of the ISRP received from theANDSF server. For example, since the ISRP indicates that a higherpriority is given to a WLAN, the UE 10 may set information indicatingthe WLAN as the eighth identification information. Note that the UE 10may select the access network indicated by the eighth identificationinformation based on the ISRP, only in a case where the ISRP is valid oractive.

As described above, the UE 10 may make a request for establishing themulti-access PDN connection by transmitting the first identificationinformation and/or the fifth identification information and/or theeighth identification information. In other words, the firstidentification information and/or the fifth identification informationand/or the eighth identification information may be informationindicating the request for establishing a multi-access PDN connection.

The PDN connectivity request message ID may be a message typerepresenting the PDN connectivity request message.

The procedure transaction ID may be information for identifying the PDNconnectivity procedure.

The APN may be an APN, to which the UE 10 requests a connection. Morespecifically, the APN may be the APN 1. The UE 10 may include the APN 1,in order to establish the multi-access PDN connection based on theNBIFOM. Here, the APN 1 may be an APN that is allowed to establish themulti-access PDN connection based on the NBIFOM and/or an APN that isallowed to perform communication based on the NBIFOM. Furthermore, theAPN may be identification information identifying the first PDNconnection.

The PDN connection ID may be an ID assigned when the PGW 30 establishesthe PDN connection in the PDN connectivity procedure, or may beinformation for uniquely identifying the PDN connection that the UE 10establishes with the PGW 30. Furthermore, the PDN connection ID may beidentification information identifying the first PDN connection The PDNconnection ID may be associated with the APN.

Note that the UE 10 may identify the first PDN connection by using theAPN and/or the PDN connection ID.

The request type may be information for identifying the type of the PDNconnectivity procedure to be requested. For example, since the UE 10performs an initial connection by using the APN 1, the request type maybe the type indicating an attach, rather than the type indicating ahandover.

The PDN type may indicate an available IP version. For example, the PDNtype may be IPv4, IPv6, or IPv4v6.

The protocol discriminator may be an identifier representing a protocoltype currently used for transmission and/or reception of the PDNconnectivity request.

The EPS bearer ID may be information identifying the EPS bearer. The EPSbearer ID may be assigned by the MME 40.

The PCO may be protocol information associated with the PDN connection.Furthermore, the PCO may include identification information on therequest. Note that the UE 10 may transmit the PCO including the firstidentification information and/or fifth identification informationand/or the eighth identification information.

The TFT may be information for identifying an IP flow for performingcommunication by using the PDN connection established in the current PDNconnectivity procedure. Note that the IP flow to be identified may varyfor each application. Thus, the TFT identifies user data of a certainapplication.

More specifically, the TFT may be constituted of a five-tuple, or may beconstituted of identification information such as the application ID.Note that the five-tuple may be constituted of a combination of one ormore of a transmission-source IP address, a transmission-destination IPaddress, a transmission-source port number, a transmission-destinationport number, and a protocol number.

Note that in the present example, when transmitting the PDN connectivityrequest, the UE 10 does not request a certain NBIFOM operation mode, andthus, the UE 10 may transmit the PDN connectivity request withoutincluding the TFT. In other words, when the UE 10 requests theestablishment of the multi-access PDN connection based on the NBIFOMwithout requesting a certain NBIFOM operation mode, the UE 10 maytransmit the PDN connectivity request without including the TFT. Morespecifically, when the UE 10 includes the first identificationinformation and/or fifth identification information and/or eighthidentification information, the UE 10 may transmit the PDN connectivityrequest without including the TFT.

Note that conventionally, the UE 10 is capable of transmit the PCOincluding information indicating an IFOM support. Here, the IFOM supportis identification information representing that the IP Flow Mobility(IFOM) is supported. Furthermore, the IFOM is a technique for switchinga communication path of a certain IP flow by using between the DualStack Mobile IPv6 (DSMIPv6) protocol. Thus, including the informationindicating the IFOM support in the PCO allows the UE 10 to switch theaccess network through which the communication of a certain IP flow isperformed.

In the present embodiment, in a case where the UE 10 includes the firstidentification information and/or the fifth identification informationand/or the eighth identification information in the PCO, the UE 10 doesnot include the IFOM support. In contrast, in a case where the UE 10includes the IFOM support in the PCO, the UE 10 does not include thefirst identification information and/or the fifth identificationinformation and/or the eighth identification information. As describedabove, it may be possible to not configure both the first identificationinformation and/or fifth identification information and/or eighthidentification information and the IFOM support to be effective toensure a clear distinction between the use of the switching of thecommunication path based on the NBIFOM and the use of the switching ofthe communication path based on the IFOM.

Thus, the UE 10 is capable of establishing either the PDN connectionsupporting the IFOM or the PDN connection supporting the NBIFOM, in theestablishment procedure of a single PDN connection. In other words, thesingle PDN connection is any one of the PDN connection supporting theNBIFOM, the PDN connection supporting the IFOM, or the single-access PDNconnection.

The MME 40 receives the PDN connectivity request transmitted from the UE10. Upon the reception of the PDN connectivity request and/or based onthe first identification information and/or fifth identificationinformation and/or eighth identification information included in the PDNconnectivity request, the MME 40 transmits a Create Session Request tothe SGW 35 (S2404).

Upon the reception of the PDN connectivity request and/or based on thefirst identification information included in the PDN connectivityrequest, the MME 40 may transmit the Create Session Request including atleast the first identification information.

Upon the reception of the PDN connectivity request and/or based on thefifth identification information and/or eighth identificationinformation included in the PDN connectivity request, the MME 40 maytransmit the Create Session Request including at least the fifthidentification information and/or eighth identification information.Furthermore, the MME 40 may include the TFT in the Create SessionRequest, upon the reception of the TFT transmitted from the UE 10.

Furthermore, the MME 40 may include the APN and/or PDN connection ID inthe Create Session Request, upon the reception of the APN and/or PDNconnection ID transmitted from the UE 10. Note that the MME 40 mayidentify the first PDN connection by using the received APN and/or PDNconnection ID.

Furthermore, the TFT may be information for identifying an IP flow thatperforms communication by using the PDN connection established in thecurrent PDN connectivity procedure. Note that the IP flow to beidentified may vary for each application. Thus, the TFT identifies userdata of a certain application.

More specifically, the TFT may be constituted of a five-tuple, or may beconstituted of identification information such as the application ID.Note that the five-tuple may be constituted of a combination of one ormore of a transmission-source IP address, a transmission-destination IPaddress, a transmission-source port number, a transmission-destinationport number, and a protocol number.

Note that in a case that none of the first identification informationand fifth identification information and/or eighth identificationinformation is included in the PDN connectivity request, the MME 40 maytransmit the Create Session Request without including the firstidentification information and/or fifth identification informationand/or eighth identification information. Moreover, in a case that thefirst identification information and/or fifth identification informationand/or eighth identification information is not included in the PDNconnectivity request, the MME 40 may perform a procedure forestablishing the single-access PDN connection.

The SGW 35 receives the Create Session Request transmitted from the MME40. Upon the reception of the PDN connectivity request and/or based onthe first identification information and/or fifth identificationinformation and/or eighth identification information included in the PDNconnectivity request, the SGW 35 transmits the Create Session Request tothe PGW 30 (S2406).

Upon the reception of the session connectivity request and/or based onthe first identification information and/or fifth identificationinformation and/or eighth identification information included in thesession connectivity request, the SGW 35 may transmit the Create SessionRequest including at least the first identification information and/orfifth identification information and/or eighth identificationinformation. Furthermore, the SGW 35 may include the TFT in the CreateSession Request.

Furthermore, the SGW 35 may include the APN and/or PDN connection ID inthe Create Session Request, upon the reception of the APN and/or PDNconnection ID transmitted from the MME 40. Note that the SGW 35 mayidentify the first PDN connection by using the received APN and/or PDNconnection ID.

Furthermore, the TFT may be information for identifying an IP flow thatperforms communication by using the PDN connection established in thecurrent PDN connectivity procedure. Note that the IP flow to beidentified may vary for each application. Thus, the TFT identifies userdata of a certain application.

More specifically, the TFT may be constituted of a five-tuple, or may beconstituted of identification information such as the application ID.Note that the five-tuple may be constituted of a combination of one ormore of a transmission-source IP address, a transmission-destination IPaddress, a transmission-source port number, a transmission-destinationport number, and a protocol number.

Note that in a case that none of the first identification informationand the fifth identification information and/or eighth identificationinformation is included in the create session request, the SGW 35 maytransmit the Create Session Request without including the firstidentification information and/or fifth identification informationand/or eighth identification information. Moreover, in a case that thefirst identification information and/or fifth identification informationand/or eighth identification information is not included in the PDNconnectivity request, the MME 40 may perform a procedure forestablishing the single-access PDN connection.

The PGW 30 receives the Create Session Request transmitted from the SGW35. Upon the reception of the Create Session Request, and/or based onthe first identification information and/or fifth identificationinformation and/or eighth identification information included in theCreate Session Request, the PGW 30 may perform an IP-CAN session updateprocedure with the PCRF 60 (S2408).

Upon the reception of the Create Session Request and/or based on thefirst identification information and/or fifth identification informationand/or eighth identification information included in the Create SessionRequest, the PGW 30 may perform the IP-CAN session update procedureincluding at least the first identification information and/or fifthidentification information and/or eighth identification information.

Furthermore, the PGW 30 may identify the first PDN connection by usingthe received APN and/or PDN connection ID, upon the reception of the APNand/or PDN connection ID transmitted from the SGW 35.

Note that the PGW 30 may perform the IP-CAN session update procedure tonotify the PCRF 60 of information on the UE 10 and/or the eNodeB 45and/or the MME 40 and/or the SGW 35.

More specifically, when the multi-access PDN connection based on theNBIFOM is to be established, the PGW 30 transmits, to the PCRF 60, theinformation indicating the access network B, the PDN connection ID, theinformation indicating that the PDN connection is the multi-access PDNconnection based on the NBIFOM, and the first identification informationand/or fifth identification information and/or eighth identificationinformation.

More specifically, when the multi-access PDN connection based on theNBIFOM is to be established, the PGW 30 transmits, to the PCRF 60, theinformation indicating the access network A, the PDN connection ID, theinformation indicating that the PDN connection is the multi-access PDNconnection based on the NBIFOM, and the first identification informationand/or fifth identification information and/or eighth identificationinformation. Alternatively, when the single-access PDN connection is tobe established, the PGW 30 transmits, to the PCRF 60, the informationindicating the access network A, the PDN connection ID, and theinformation indicating that the PDN connection is the single-access PDNconnection.

Note that the PDN connection ID may be an ID assigned when the PGW 30establishes the PDN connection in the PDN connectivity procedure, or maybe information for uniquely identifying the PDN connection that the UE10 establishes with the PGW 30.

Furthermore, upon the reception of the first identification informationand/or fifth identification information and/or eighth identificationinformation, the PCRF 60 may transmit, to the PGW 30, a control messagein the IP-CAN session update procedure with the PGW 30, the controlmessage including at least the second identification information and/orseventh identification information and/or ninth identificationinformation. The detailed description of the second identificationinformation and/or the seventh identification information and/or theninth identification information will be described later.

Note that the PCRF 60 may perform the IP-CAN session update procedure tonotify the PGW 30 of the charging information and/or the QoS controlinformation and/or the routing information.

Upon the reception of the Create Session Request or the completion ofthe IP-CAN session update procedure, and/or based on the firstidentification information and/or fifth identification informationand/or eighth identification information included in the Create SessionRequest, and/or based on the second identification information and/orseventh identification information and/or ninth identificationinformation included in the IP-CAN session update procedure, the PGW 30transmits a Create Session Response to the SGW 35 (S2410).

Upon the reception of the Create Session Request or the completion ofthe IP-CAN session update procedure, and/or based on the firstidentification information and/or fifth identification informationand/or eighth identification information included in the Create SessionRequest, and/or based on the second identification information and/orseventh identification information and/or ninth identificationinformation included in the IP-CAN session update procedure, the PGW 30transmits the Create Session Response including at least the secondidentification information and/or seventh identification informationand/or ninth identification information.

Furthermore, the PGW 30 may include the PDN Address and/or the PDNconnection ID and/or the TFT and/or the bearer identificationinformation identifying the default bearer in the Create SessionResponse.

Note that a method by which the PGW 30 acquires the secondidentification information and/or seventh identification informationand/or ninth identification information is not limited to theabove-described method for acquiring the seventh identificationinformation from the PCRF 60 in the IP-CAN session update procedure, andanother example may be employed. For example, the PGW 30 may create thesecond identification information and/or seventh identificationinformation and/or ninth identification information and transmit theCreate Session Response including the second identification informationand/or seventh identification information and/or ninth identificationinformation, without acquiring from the PCRF 60 in the IP-CAN sessionupdate procedure.

Here, the second identification information may be the NBIFOM capabilityrepresenting that the network supports the NBIFOM. Note that the NBIFOMcapability may be information indicating the provision of the functionof establishing the multi-access PDN connection.

Here, the seventh identification information may be the Allowed Moderepresenting the NBIFOM operation mode that is allowed for themulti-access PDN connection based on the NBIFOM to be established. Inother words, the seventh identification information may be the operationmode allowed by the operator.

As described above, the UE 10 may transmit the seventh identificationinformation to make a notification of the mode of the multi-access PDNconnection. In other words, the UE 10 may transmit the seventhidentification information to permit the establishment of themulti-access PDN connection corresponding to the mode indicated by theseventh identification information. Note that the mode indicated by theseventh identification information may be selected by the PCRF 60 or thePGE 30. Note that the PCRF 60 or the PGE 30 may transmit the modeindicated by the fifth identification information as the seventhidentification information, in a case where the PCRF 60 or the PGE 30allows the establishment of the multi-access PDN connection in the modeindicated by the fifth identification information requested by the UE10.

Note that the PCRF 60 or the PGW 30 may determine the Allowed Mode andthe seventh identification information based on the operator policy. Forexample, a policy that allows the establishment of only the PDNconnection of the UE-Initiated mode, a policy that allows theestablishment of only the PDN connection of the Network-Initiated mode,a policy that allows the establishment of both modes, a policy thatprohibits the establishment of both modes, and the like may be managed.

Note that the PCRF 60 or the PGW 30 may acquire the operator policy fromthe HSS 50 or the like. Alternatively, an operator policy created by anadministrator may be stored.

In addition, for the operator policy, a policy different for eachsubscriber may be managed. Alternatively, a policy different for eachAPN may be managed. For example, for each APN, a different Allowed Modefor the PDN connection to be established may be managed.

On the basis of the Allowed Mode, the PCRF 60 or the PGW 30 may includethe allowed operation mode in the seventh identification information.

In other words, when only the Network-Initiated mode is allowed, thePCRF 60 or the PGW 30 may include the Network-Initiated mode in theseventh identification information. Alternatively, when only theUE-Initiated mode is allowed, the PCRF 60 or the PGW 30 may include theUE-Initiated mode in the seventh identification information.

Note that when both the UE-Initiated mode and the Network-Initiated modeare allowed, the seventh identification information may include both theoperation modes. Alternatively, when both the UE-Initiated mode and theNetwork-Initiated mode are allowed and a default operation mode isconfigured, the seventh identification information may include only thedefault operation mode. Note that which one of the UE-Initiated mode andthe Network-Initiated mode is defined as the default operation mode maybe configured based on the operator policy.

Note that, when none of the operation modes is allowed for establishmentof the PDN connection, the PCRF 60 may transmit, to the PGW 30, thecause information indicating that the requested operation mode is notallowed.

In a case that none of the operation modes is allowed for establishmentof the PDN connection, the PGW 30 need not notify the MME 40 of theseventh identification information via the SGW 35.

In a case that none of the operation modes is allowed for establishmentof the PDN connection, the PGW 30 may transmit, to the MME 40 via theSGW 35, the Create Session Response including the cause informationindicating that the Requested Operation Mode is not allowed.

In a case that none of the operation modes is allowed for establishmentof the PDN connection, the PGW 30 may notify the MME 40 that there is noallowed operation via the SGW 35.

As described above, on the basis of the Allowed Mode, the PCRF 60 or thePGW 30 may regard an operation mode that is allowed for establishment ofthe PDN connection as the seventh identification information.

Note that when the Network-Initiated mode is not included in the seventhidentification information, the PCRF 60 need not transmit the TFT to thePGW 30.

In other words, note that only when the Network-Initiated mode isincluded in the seventh identification information, the PCRF 60 maytransmit the TFT to the PGW 30.

Note that in a case that the Network-Initiated mode is not included inthe seventh identification information, the PGW 30 need not transmit theTFT to the MME 40 via the SGW 35. Thus, in this case, the PGW 30 neednot include either the TFT or the PDN address in the Create SessionResponse.

Note that, in other words, only in a case that the Network-Initiatedmode is included in the seventh identification information, the PGW 30may transmit the TFT to the MME 40 via the SGW 35. Thus, in this case,the PGW 30 may include the TFT and the PDN address (PDN Address) in theCreate Session Response.

The PDN address may be an IP address assigned to the UE 10. For example,the PDN address may be an IPv4 address, or an IPv6 prefix and aninterface ID for constituting an IPv6 address. Here, the PGW 30 mayassign the IP address of the UE 10. Moreover, the PGW 30 may include theIP address assigned to the UE 10 in the PDN address.

Furthermore, the PDN connection ID may be information for uniquelyidentifying the PDN connection established between the UE 10 and the PGW30. The PDN connection ID may be assigned by the PGW 30, or may beassigned by the MME 40. In other words, the PGW 30 may assign the PDNconnection ID.

Furthermore, the ninth identification information may be informationindicating a default access (Default Assess) in the multi-access PDNconnection. Note that the ninth identification information may beinformation indicating the 3GPP access or the WLAN access. The 3GPPaccess may be an access system that is not the WLAN access. Morespecifically, the 3GPP access may be information indicating an accessnetwork including the E-UTRAN access, the UTRAN access, and the GERANaccess.

Alternatively, the ninth identification information may include moredetailed information. For example, the ninth identification informationmay be one of E-UTRAN access, UTRAN access and GERAN access.

As described above, the PCRF 60 or the PGE 30 may transmit the ninthidentification information to notify the UE 10 of the default access forthe multi-access PDN connection. In other words, the PCRF 60 or the PGE30 may transmit the ninth identification information to request theestablishment of the multi-access PDN connection in which the accessnetwork indicated by the ninth identification information is used as thedefault access. Note that the access network indicated by the ninthidentification information may be selected by the PCRF 60 or the PGE 30.Note that the PCRF 60 or the PGE 30 may transmit the access networkindicated by the eighth identification information as the ninthidentification information, in a case where the PCRF 60 or the PGE 30allows the establishment of the multi-access PDN connection for thedefault access indicated by the eighth identification informationrequested by the UE 10.

As described above, the establishment of the multi-access PDN connectionis permitted by transmitting the second identification informationand/or the seventh identification information and/or the ninthidentification information. In other words, the second identificationinformation and/or the seventh identification information and/or theninth identification information may be information indicating that themulti-access PDN connection is to be established or establishment of themulti-access PDN connection is permitted.

Note that, the PCRF 60 and the PGW 30 may be configured to transmit theninth identification information in a case where a default bearer hasnot been established for the multi-access PDN connection, theestablishment of which is to be requested, and may be configured not totransmit the ninth identification information in a case where thedefault bearer has already been established for the multi-access PDNconnection.

More specifically, the PCRF 60 and the PGW 30 may be configured totransmit the ninth identification information when establishing a newmulti-access PDN connection, and not to transmit the ninthidentification information when adding a transfer path in a state inwhich the default bearer is established for the multi-access PDNconnection through the LTE access network.

The SGW 35 receives the Create Session Response transmitted from the PGW30. Upon the reception of the Create Session Response and/or based onthe second identification information and/or seventh identificationinformation and/or ninth identification information included in theCreate Session Response, the SGW 35 transmits the Create SessionResponse to the MME 40 (S2412).

Upon the reception of the Create Session Response and/or based on thesecond identification information and/or seventh identificationinformation and/or ninth identification information included in theCreate Session Response, the SGW 35 may transmit the Create SessionResponse including at least the second identification information and/orseventh identification information and/or ninth identificationinformation.

Furthermore, the SGW 35 may include the PDN Address and/or the PDNconnection ID and/or the TFT in the Request Session Response.

The MME 40 receives the Create Session Response transmitted from the SGW35. Upon the reception of the Create Session Response and/or based onthe second identification information and/or seventh identificationinformation and/or ninth identification information included in theCreate Session Response, the MME 40 transmit the Activate default EPSbearer context request to the eNodeB 45 (S2414).

Upon the reception of the Create Session Response and/or based on thesecond identification information and/or seventh identificationinformation and/or ninth identification information included in theCreate Session Response, the MME 40 may transmit at least an Activatedefault EPS bearer context request message identity (Activate defaultEPS bearer context request message ID), a Procedure transaction ID, anAPN, a PDN Address, a protocol discriminator, an EPS bearer ID, and EPSQoS included in the Activate default EPS bearer context request. The MME40 may further include at least the second identification informationand/or seventh identification information and/or ninth identificationinformation in the Activate default EPS bearer context request.Moreover, upon the reception of the Create Session Response and/or basedon the second identification information and/or seventh identificationinformation and/or ninth identification information included in theCreate Session Response, the MME 40 may include the PCO and/or the ESMCause and/or the TFT and/or the bearer identification informationidentifying the default bearer, and/or the PDN connection ID and/or thePDN connection attribute information, in the Activate default EPS bearercontext request. Note that the MME 40 may transmit the PCO including thesecond identification information and/or seventh identificationinformation and/or ninth identification information and/or the TFTand/or the bearer identification information identifying the defaultbearer and/or the PDN connection ID.

Here, the Activate default EPS bearer context request message ID may bea message type representing the Activate default EPS bearer contextrequest message.

The APN may be an APN, to which the UE 10 is allowed to connect. Morespecifically, the APN may be the APN 1. The APN 1 may be an APN that isallowed to establish the multi-access PDN connection based on theNBIFOM. The MME 40 may include the APN 1 in the Activate default EPSbearer context request.

The PDN address may be an IP address assigned to the UE 10. For example,the PDN address may be an IPv4 address, or an interface ID forconstituting an IPv6 address.

The EPS QoS may indicate a state representing QoS of an EPS bearer.

The PDN connection attribute information may be information indicatingthat the PDN connection established in the present PDN connectivityprocedure is the multi-access PDN connection, and/or informationindicating that user data transmitted and/or received by using the PDNconnection established in the PDN connection the present PDNconnectivity procedure is allowed to be transmitted and/or receivedthrough the access network A and the access network B, and/orinformation indicating that the PDN connection established in thepresent PDN connectivity procedure is the multi-access PDN connectionbased on the NBIFOM of the operation mode indicated by the seventhidentification information.

Note that the UE 10 may transmit the Activate default EPS bearer contextrequest message that further includes the connectivity type indicatingthe type of the PDN connection and/or the WLAN offload permissioninformation (WLAN offload acceptablity) indicating whether the WLANoffload can be performed. Furthermore, the MME 40 may transmit theconnectivity type or the WLAN offload permission information includingthe PDN connection attribute information.

ESM Cause may be information representing that the PDN type of the PDNaddress assigned to the UE 10 is different from the PDN type requestedby the UE 10 in the PDN connectivity request.

Note that the MME 40 and/or the PGW 30 may include the secondidentification information and/or the seventh identification informationand/or the ninth identification information in the PCO. However, in acase where the MME 40 and/or the PGW 30 includes the secondidentification information and/or the seventh identification informationand/or the ninth identification information in the PCO, the MME 40and/or the PGW 30 does not include the IFOM support. In contrast, in acase where the MME 40 and/or the PGW 30 includes the IFOM support in thePCO, the MME 40 and/or the PGW 30 does not include the secondidentification information and/or the seventh identification informationand/or the ninth identification information. As described above, it maybe possible to not configure both the second identification informationand/or seventh identification information and/or ninth identificationinformation and the IFOM support to be effective to ensure a cleardistinction between the use of the switching of the communication pathbased on the NBIFOM and the use of the switching of the communicationpath based on the IFOM.

The eNodeB 45 receives the Activate default EPS bearer context requesttransmitted from the MME 40. Upon the reception of the Activate defaultEPS bearer context request, the eNodeB 45 transfers the Activate defaultEPS bearer context request to the UE 10.

The eNodeB 45 may transmit at least an RRC connection configurationrequest (RRC Connection Reconfiguration) to the UE 10 with an Activatedefault EPS bearer context request (S2416).

The UE 10 receives the RRC connection configuration request transmittedfrom the eNodeB 45. Furthermore, the UE 10 receives the Activate defaultEPS bearer context request transmitted from the MME 40 and transferredby the eNodeB 45.

Upon the reception of the RRC connection configuration request, the UE10 transmits the RRC connection configuration complete (RRC ConnectionReconfiguration Complete) to the eNodeB 45 (S2418).

The eNodeB 45 receives the RRC connection configuration completetransmitted from the UE 10. The eNodeB 45 transmits bearer configurationto the MME 40 in response to the RRC connection configuration complete.

The MME 40 receives the bearer configuration transmitted from the eNodeB45 (S2420).

Upon the reception of the Activate default EPS bearer context requestand/or based on the second identification information and/or seventhidentification information and/or ninth identification informationincluded in the Activate default EPS bearer context request, the UE 10transmits an Activate default EPS bearer context accept or an Activatedefault EPS bearer context reject to the MME 40 (S2422) (S2424).

The UE 10 may transmit at least an Activate default EPS bearer contextaccept message identity (Activate default EPS bearer context acceptmessage ID), a procedure transaction ID, a protocol discriminator, andan EPS bearer ID included in the Activate default EPS bearer contextaccept.

The UE 10 may transmit at least an Activate default EPS bearer contextreject message identity (Activate default EPS bearer context rejectmessage ID), a Procedure transaction ID, a protocol discriminator, anEPS bearer ID, and an ESM Cause included in the Activate default EPSbearer context reject.

Furthermore, the UE 10 may include the PCO in the Activate default EPSbearer context accept and/or the Activate default EPS bearer contextreject.

Furthermore, in a case that multiple INFOM operation modes are includedin the seventh identification information, the UE 10 may include atleast the fifth identification information in the Activate default EPSbearer context accept and/or the Activate default EPS bearer contextreject. In other words, when multiple INFOM operation modes are allowed,the UE 10 may select one of the allowed modes and transmit the fifthidentification information including the selected mode.

Here, the fifth identification information may be the Mode Indicationrepresenting an NBIFOM operation mode for the multi-access PDNconnection whose establishment is requested by the UE 10. Note that theUE 10 may include the UE-Initiated mode or the Network-Initiated mode inthe fifth identification information.

Specifically, in a case that the UE-Initiated mode and theNetwork-Initiated mode are included in the seventh identificationinformation included in the Activate default EPS bearer context request,the UE 10 may include the UE-Initiated mode or the Network-Initiatedmode in the fifth identification information.

Which of the UE-Initiated mode and the Network-Initiated mode is to beincluded in the fifth identification information may be determined basedon the UE policy. Note that the UE policy may be any informationconfigured for the UE 10. For example, the UE policy may be informationconfigured by a user.

Here, the Activate default EPS bearer context accept message ID may be amessage type representing the Activate default EPS bearer context acceptmessage.

The Activate default EPS bearer context reject message ID may be amessage type representing the Activate default EPS bearer context rejectmessage.

The ESM Cause may be information representing a reason of rejecting theActivate default EPS bearer context request.

Thus, the UE 10 changes its state to the third initial state (S2310).

That is, the UE 10 can establish an additional transfer path through theLTE access network A, based on the transition to the first initial stateand based on the Operation mode of the first PDN connection.

Specifically, the UE 10 can perform the Attach procedure and the PDNconnectivity procedure on the LTE access network A to establish theadditional transfer path via the eNB 45, based on the transition to thefirst initial state and based on the fact that the first PDN connectionis in the Network-initiated mode. Note that the transfer path may be abearer and/or a communication path.

More specifically, the UE 10 performs the Attach procedure, establishesthe second PDN connection between the PGW_B selected using the APN 2 andthe UE 10, and then performs the PDN connectivity procedure, so that atransfer path through the LTE access network can be added to the firstPDN connection between the PGW_A selected using the APN 1 and the UE 10.Note that the transfer path may be a bearer and/or a communication path.That is, in the state in which a default bearer through the WLAN isestablished, a default bearer through the LTE access network for thefirst PDN connection can be further established.

Alternatively, the UE 10 can perform the Attach procedure and the PDNconnectivity procedure on the LTE access network A to establish theadditional transfer path via the eNB 45, based on transition to thefirst initial state and based on the Routing Rule of the first PDNconnection established in the UE-initiated mode. Note that the transferpath may be a bearer and/or a communication path.

Specifically, the UE 10 performs the Attach procedure, establishes thesecond PDN connection between the PGW_B selected using the APN 2 and theUE 10, and then performs the PDN connectivity procedure, so that atransfer path through the LTE access network can be added to the firstPDN connectivity between the PGW_A selected using the APN 1 and the UE10. Note that the transfer path may be a bearer and/or a communicationpath.

Furthermore, the UE 10 can establish an additional transfer path throughthe LTE access network A, based on the transition to the second initialstate and based on the Operation mode of the first PDN connection.

Specifically, the UE 10 can perform the PDN connectivity procedure onthe LTE access network A to establish the additional transfer path viathe eNB 45, based on the transition to the second initial state andbased on the fact that the first PDN connection is in theNetwork-initiated mode. Note that the transfer path may be a bearerand/or a communication path.

More specifically, the UE 10 performs the PDN connectivity procedure, sothat a transfer path through the LTE access network can be added to thefirst PDN connectivity between the PGW_A selected using the APN 1 andthe UE 10. Note that the transfer path may be a bearer and/or acommunication path.

Alternatively, the UE 10 can perform the PDN connectivity procedure onthe LTE access network A to establish the additional transfer path viathe eNB 45, based on transition to the second initial state and based onthe Routing Rule of the first PDN connection established in theUE-initiated mode. Note that the transfer path may be a bearer and/or acommunication path.

Specifically, the UE 10 performs the PDN connectivity procedure, so thata transfer path through the LTE access network can be added to the firstPDN connectivity between the PGW_A selected using the APN 1 and the UE10. Note that the transfer path may be a bearer and/or a communicationpath.

In this way, with respect to the first PDN connection, the UE 10 and thePGW 30 establish a new default bearer. The UE 10 and the PGW 30 storethe identification information of the default bearer established in thePDN connectivity procedure and the information identifying the LTEaccess network in association with each other, in response to completionof the PDN connectivity procedure through the LTE access network.Furthermore, the information identifying the LTE access network may beinformation indicating a 3GPP access or information indicating anE-UTRAN access.

Note that the UE 10 performs data transmission and reception using thedefault bearer when the UE 10 does not receive the TFT or transmits andreceives the user data not matching the held TFT. When multiple defaultbearers are established, the UE 10 is capable of selecting a defaultbearer for transmitting and/or receiving data based on the defaultaccess, and is capable of transmitting and/or receiving data by usingthe selected default bearer.

Here, the default access may be default access indicated by the ninthidentification information. In a case where the UE 10 does not receivethe ninth identification information at the time of establishing thesecond default bearer for the first PDN connection, the UE 10 may selectthe default access based on the ninth identification informationreceived at the time of establishing the first default bearer for thefirst PDN connection, and transmit and/or receive data using theselected default bearer.

Furthermore, the PGW 30 performs data transmission and/or receptionusing the default bearer when the PGW 30 does not receive the TFT ortransmits and/or receives the user data not matching the held TFT. Whenthe PGW 30 establishes multiple default bearers with the UE 10, the PGW30 is capable of selecting a default bearer for transmitting and/orreceiving data based on the default access, and is capable oftransmitting and/or receiving data by using the selected default bearer.Here, the default access may be default access indicated by the ninthidentification information.

Here, the default access may be default access indicated by the ninthidentification information. In a case where the PGW 30 does not transmitthe ninth identification information at the time of establishing thesecond default bearer for the first PDN connection, the PGW 30 mayselect the default access based on the ninth identification informationtransmitted at the time of establishing the first default bearer for thefirst PDN connection, and transmit and/or receive data using theselected default bearer.

In this way, in a case where the UE 10 and the PGE 30 are capable ofacquiring the default access in the state where the second defaultbearer is not established, the PDN connectivity establishment procedurefor establishing the second unnecessary default bearer is eliminated.For example, in a case that the communication path through the LTEaccess network is established by the additional PDN connectionprocedure, there may be a case in which no user data that selects thecommunication path through the LTE access network exists, and thecommunication path is not used, depending on the Routing Rule based onthe TFT or the like. Learning a default access beforehand eliminates theestablishment of such an unnecessary communication path between the UE10 and the PGW 30, and therefore reduces transmission and/or receptionof control messages for unnecessary communication path establishment,consumption of the resources for the communication path, and the like.

In this way, if the UE 10 and the PGE 30 can acquire the default accessin the state where the second default bearer is not established, the UE10 can determine whether performing the PDN connection establishmentprocedure for establishing a new default bearer for the multi-access PDNconnection based on the information on the default access, when the UE10 is newly located in a serving area of an LTE access network.

For example, in a case that the default access indicates a WLAN network,the multi-access access PDN connection is in the UE-Initiated mode, andthe Routing Rule does not include user data to which priority is givento communicate by the communication path through the LTE, it is notnecessary to immediately perform the additional transfer pathestablishment procedure for establishing the default bearer through theLTE.

3. Third Embodiment

A third embodiment of the present invention will be described. The PDNconnection such as a multi-access PDN connection established by the UE10 through the TWAG 74 is established through the ePDG 65, in the firstembodiment.

Note that configurations of the mobile communication system in thepresent embodiment and the respective devices, such as the UE 10, thePGW 30, and the MME 40 included in the mobile communication system maybe similar to those in the first embodiment, and the descriptions areomitted.

Note that the configuration of the ePDG 65 may be similar to the TWAG74, which has been described in the first embodiment with reference toFIG. 3. A difference between the ePDG 65 and the TWAG 74 is that theePDG 65, the WLAN ANb 75 connects with the core network 90 while theTWAG 74 connects the WLAN ANa 70 with the core network 90.

Note that the processes of the ePDG 65 in the present embodiment may besimilar to the processes of the TWAG 74, which has been described in thefirst embodiment. The processes of the respective devices such as the UE10, the PGW 30, the MME 40, and the PCRF 60 may be similar to theprocesses of the respective devices described in the first embodiment.

The processes performed for the TWAG 74 among the processes of the UE 10and the PGW 30 is performed for the ePDG 65.

Furthermore, the PDN connectivity request message described in the firstembodiment may be a control message in an IKEv2 tunnel establishmentprocedure and an IKEv2 authentication request message transmitted fromthe UE 10 to the ePDG 65.

Therefore, the various information items included in the IKEv2authentication message in the present embodiment may be similar to thevarious information items included in the PDN connectivity requestmessage described in the first embodiment. Furthermore, processes of theUE 10 and the ePDG 65 regarding transmission and/or reception of theIKEv2 authentication message may be similar to processes of the UE 10and the TWAG 74 regarding transmission and/or reception of the PDNconnectivity request message described in the first embodiment.

The PDN connectivity accept message described in the first embodimentmay be a control message in the IKEv2 tunnel establishment procedure,and a permission message in response to the IKEv2 authentication requestmessage transmitted from the ePDG 65 to the UE 10.

Therefore, the various information items included in the permissionmessage in the present embodiment may be similar to the variousinformation items included in the PDN connectivity accept messagedescribed in the first embodiment. Furthermore, processes of the UE 10and the ePDG 65 regarding transmission and/or reception of thepermission message may be similar to processes of the UE 10 and the TWAG74 regarding transmission and/or reception of the PDN connectivityaccept message described in the first embodiment.

The PDN connectivity reject message described in the first embodimentmay be a control message in the IKEv2 tunnel establishment procedure,and a reject message in response to the IKEv2 authentication requestmessage transmitted from the ePDG 65 to the UE 10.

Therefore, the various information items included in the permissionmessage in the present embodiment may be similar to the variousinformation items included in the PDN connectivity reject messagedescribed in the first embodiment. Furthermore, processes of the UE 10and the ePDG 65 regarding transmission and/or reception of the rejectmessage may be similar to processes of the UE 10 and the TWAG 74regarding transmission and reception of the PDN connectivity rejectmessage described in the first embodiment.

Thus, the UE 10 performs communication control regarding themulti-access PDN connection via the ePDG 65.

4. Fourth Embodiment

A fourth embodiment of the present invention will be described. The PDNconnection such as a multi-access PDN connection established by the UE10 through the TWAG 74 is established through the ePDG 65, in the secondembodiment.

Note that configurations of the mobile communication system in thepresent embodiment and the respective devices such as the UE 10, the PGW30, and the MME 40 included in the mobile communication system may besimilar to those in the second embodiment, and the descriptions areomitted.

Note that the configuration of the ePDG 65 may be similar to the TWAG74, which has been described in the second embodiment with reference toFIG. 3. A difference between the ePDG 65 and the TWAG 74 is that theePDG 65, the WLAN ANb 75 connects with the core network 90 while theTWAG 74 connects the WLAN ANa 70 with the core network 90.

Note that the processes of the ePDG 65 in the present embodiment may besimilar to the processes of the TWAG 74, which has been described in thesecond embodiment. The processes of the respective devices such as theUE 10, the PGW 30, the MME 40, and the PCRF 60 may be similar to theprocesses of respective devices described in the second embodiment. Theprocesses performed for the TWAG 74 among the processes of the UE 10 andthe PGW 30 is performed for the ePDG 65.

Furthermore, the PDN connectivity request message described in thesecond embodiment may be a control message in an IKEv2 tunnelestablishment procedure and an IKEv2 authentication request messagetransmitted from the UE 10 to the ePDG 65.

Therefore, the various information items included in the IKEv2authentication message in the present embodiment may be similar to thevarious information items included in the PDN connectivity requestmessage described in the second embodiment. Furthermore, processes ofthe UE 10 and the ePDG 65 regarding transmission and/or reception of theIKEv2 authentication message may be similar to processes of the UE 10and the TWAG 74 regarding transmission and/or reception of the PDNconnectivity request message described in the second embodiment.

The PDN connectivity accept message described in the second embodimentmay be a control message in the IKEv2 tunnel establishment procedure,and a permission message in response to the IKEv2 authentication requestmessage transmitted from the ePDG 65 to the UE 10.

Therefore, the various information items included in the permissionmessage in the present embodiment may be similar to the variousinformation items included in the PDN connectivity accept messagedescribed in the second embodiment. Furthermore, processes of the UE 10and the ePDG 65 regarding transmission and/or reception of thepermission message may be similar to processes of the UE 10 and the TWAG74 regarding transmission and/or reception of the PDN connectivityaccept message described in the second embodiment.

The PDN connectivity reject message described in the second embodimentmay be a control message in the IKEv2 tunnel establishment procedure,and a reject message in response to the IKEv2 authentication requestmessage transmitted from the ePDG 65 to the UE 10.

Therefore, the various information items included in the permissionmessage in the present embodiment may be similar to the variousinformation items included in the PDN connectivity reject messagedescribed in the second embodiment. Furthermore, processes of the UE 10and the ePDG 65 regarding transmission and/or reception of the rejectmessage may be similar to processes of the UE 10 and the TWAG 74regarding transmission and/or reception of the PDN connectivity rejectmessage described in the second embodiment.

Thus, the UE 10 can perform communication control regarding themulti-access PDN connection via the ePDG 65.

5. Modification

Additionally, the programs run on the devices in the embodiments areeach configured to control a CPU (program causing a computer tofunction) so as to realize the functions of the above-describedembodiments. The information handled by these devices is temporarilyheld in a transitory storage device (RAM, for example) at the time ofprocessing, and is then stored in various storage devices such as a ROMand an HDD, read out by the CPU as necessary, and edited and written.

Here, a semiconductor medium (a ROM, a non-volatile memory card, or thelike, for example), an optical recording medium/magneto-opticalrecording medium (a digital versatile disc (DVD), a magneto optical disc(MO), a mini disc (MD), a compact disc (CD), a BD, or the like, forexample), a magnetic recording medium (magnetic tape, a flexible disk,or the like, for example), and the like can be given as examples ofrecording media for storing the programs. In addition to realizing thefunctions of the above-described embodiments by executing loadedprograms, the functions of the present invention are realized by theprograms running cooperatively with an operating system, otherapplication programs, or the like in accordance with instructionsincluded in those programs.

For delivering these programs to the market, the programs can be storedin a portable recording medium, or can be transferred to a servercomputer connected via a network such as the Internet. In this case, astorage device in a server computer is also included in the presentinvention.

Additionally, each device in the above-described embodiment may bepartially or completely realized as large scale integration (LSI)circuit, which is a typical integrated circuit. The functional blocks ofeach device may be individually realized as chips, or may be partiallyor completely integrated into a chip. Furthermore, a circuit integrationtechnique is not limited to the LSI, and may be realized with adedicated circuit or a general-purpose processor. Furthermore, in a casewhere advances in semiconductor technology produce circuit integrationtechnology capable of replacing the LSI, it is needless to say that suchintegrated circuits based on the technology are applicable.

Additionally, although, for the above-described embodiments, the LTE andthe WLAN (IEEE 802.11a/b/n, for example) have been descried as examplesof the radio access network, the connections may be made with WiMAXinstead of the WLAN.

REFERENCE SIGNS LIST

-   9 Communication system-   10 UE-   30 PGW-   35 SGW-   40 MME-   45 eNB-   50 HSS-   55 AAA-   60 PCRF-   65 ePDG-   70 WLAN ANa-   74 TWAG-   75 WLAN ANb-   80 LTE AN-   90 Core network-   100 PDN

The invention claimed is:
 1. A User Equipment (UE) for establishing aPacket Data Network (PDN) connection over a WLAN, the UE comprising: LTEinterface circuitry configured to: transmit a PDN connectivity requestmessage to a Mobility Management Entity (MME), in a case where anEvolved Universal Terrestrial Radio Access Network (E-UTRAN) is added tothe PDN connection being established over the WLAN, and receive anActivate default EPS bearer context request message from the MME; and acontroller, wherein in a case that a Network-based IP flow mobility(NBIFOM) mode of the PDN connection is a UE-initiated NBIFOM mode, thePDN connectivity request message includes first information indicating adefault access selected by the UE, the Activate default EPS bearercontext request message includes second information indicating a defaultaccess determined by a Policy and Charging Rule Function (PCRF), and thecontroller is configured to: detect the default access indicated by thesecond information based on reception of the Activate default EPS bearercontext request message; and route a packet not matching any routingfilter to the default access indicated by the second information.
 2. TheUE according to claim 1, wherein the first information and the secondinformation indicate a 3GPP access or a non-3GPP access, respectively.3. The UE according to claim 2, wherein the second information isinformation determined by the PCRF verifying the first information. 4.The UE according to claim 1, wherein the second information isinformation determined by the PCRF verifying the first information. 5.The UE according to claim 1, the UE further comprising WLAN interfacecircuitry configured to: in order to setup the PDN connection, transmita second PDN connectivity request message to a Trusted WLAN AccessGateway (TWAG); and receive a PDN connectivity accept message from theTWAG, wherein the second PDN connectivity request message includes thirdinformation indicating a requested NBIFOM mode, the PDN connectivityaccept message includes fourth information indicating a NBIFOM modeselected by the PCRF or a PDN Gateway (PGW), and the controllerconsiders a NBIFOM mode indicated by the fourth information as a NBIFOMmode of the PDN connection based on reception of the PDN connectivityaccept message.
 6. A communication method performed by a User Equipment(UE) for establishing a Packet Data Network (PDN) connection over aWLAN, the communication method comprising: transmitting a PDNconnectivity request message to a Mobility Management Entity (MME), in acase where an Evolved Universal Terrestrial Radio Access Network(E-UTRAN) is added to the PDN connection being established over theWLAN, and receiving an Activate default EPS bearer context requestmessage from the MME, wherein in a case that a Network-based IP flowmobility (NBIFOM) mode of the PDN connection is a UE-initiated NBIFOMmode, the PDN connectivity request message includes first informationindicating a default access selected by the UE, the Activate default EPSbearer context request message includes second information indicating adefault access determined by a Policy and Charging Rule Function (PCRF),and the communication method further comprising: detecting the defaultaccess indicated by the second information based on reception of theActivate default EPS bearer context request message; and routing apacket not matching any routing filter to the default access indicatedby the second information.
 7. The communication method according toclaim 6, wherein the first information and the second informationindicate a 3GPP access or a non-3GPP access, respectively.
 8. Thecommunication method according to claim 6, wherein the secondinformation is information determined by the PCRF verifying the firstinformation.
 9. The communication method according to claim 6, thecommunication method further comprising: in order to setup the PDNconnection, transmitting a second PDN connectivity request message to aTrusted WLAN Access Gateway (TWAG); and receiving a PDN connectivityaccept message from the TWAG, wherein the second PDN connectivityrequest message includes third information indicating a requested NBIFOMmode, the PDN connectivity accept message includes fourth informationindicating a NBIFOM mode selected by the PCRF or a PDN Gateway (PGW),and the UE considers a NBIFOM mode indicated by the fourth informationas a NBIFOM mode of the PDN connection based on reception of the PDNconnectivity accept message.